The protected wetland area in Palo Verde National Park, home to thousands of resident and migratory birds

Study by Madison Deile, Alyssa Risch, & Mary Thelen

In wetlands, such as those in Palo Verde National Park, food resources are abundant for bird populations. Therefore, there is less competition between species and individuals so different species often forage together benefitting from the extra protection from predation. This leads to less vigilance in the birds as well, increasing foraging efficiency (Sridhar et al., 2009; Weller, 1999). The goal of this study was to determine how grouping patterns of species would vary depending on weather, time of day, and species’ diets. Our experiment involved the observation of birds in the wetland at Palo Verde National Park during the morning, afternoon, and evening. We recorded which species were present, grouping pattern (individual, same-species group, mixed-species group), and microhabitat (shore, mud, vegetation, open water). We used the data from the Organization for Tropical Studies to find the average scalar wind speed for each time period we observed. We also researched typical diets of every species present and grouped them into either mainly vegetation, invertebrates, or fish. We found that there was a higher percentage groups of species with completely different diets (53%) than there were groups of species with overlapping diets (47%), suggesting that birds which group together tend to have different diets, possibly to avoid competition. We found no significant difference between grouping patterns and wind speeds. There was also no significant difference between grouping patterns and time of day, but further tests suggested that more mixed species groups are present during the morning than other times of the day. Future studies could quantify abundance in each group to further learn about species and group behaviors. This study could also be repeated during the wet season to see how other biophysical variables affect bird grouping behavior.

(L) Alyssa Risch observes birds. (R) A Purple Gallinule, common in the wetlands of Palo Verde.

Model coral snake waiting for would-be predators.

Study by Elizabeth Luotto, Kackenzie Korbel, & Logan Goettl

Mimicry is relatively common in the animal world as it offers a less energetically expensive form of defense.  The physical appearance of a mimic, such as the coloring or banding, resembles a dangerous or defended model species.  Mimics do not have the energetic costs of producing poison or other such defenses as the models do, but they may still benefit by confusing potential predators.  In Palo Verde National Park (PVNP), Costa Rica, the venomous and brightly banded coral snake is abundant.  This coral snake has few natural predators due to the high danger involved with catching and eating it.  However, in PVNP there are very few mimics of the coral snake.  In this study, we wanted to explore how predators interacted with various model snakes that looked both similar and different to the coral snake.  To do this we crafted sets of four model snake types: a coral snake with the traditional black yellow red yellow banding, a mimic coral snake with black red banding, an all red snake, and a brown and black banded snake modeled after the locally abundant Costa Rican cat-eyed snake.  Snakes were set out in three microhabitat locations: by the wetlands, in the forest, and on higher elevation rock faces.  The snakes were checked for marks in the morning and evening to capture interactions from both diurnal and nocturnal predators.  Results of a chi-squared test showed that there was no significant difference between the frequency of attacks based on snake model type.  There was also no significant difference between the amount of harm (cm of snake damaged) based on snake model type (P = 0.1218).  These results support the claim that predators did not avoid coral snakes or their mimics.  We cite these results as a potential explanation for why there is limited abundance of coral snake mimics in PVNP, as there is no apparent benefit or predator avoidance, and suggest this as a future area of research.

Model snakes on the left, and an attacked model on the right.

Josh Schauer (L) and Brady Hartman (R) record responses of acacia ants

Study by Alex Morrison, Sophia Kruger, Brady Hartman, & Josh Schauer

In nature, mutualistic relationships are rare, and therefore they are well studied. One of the best studied relationships of this kind in Costa Rica—and in Palo Verde National Park—is between the Acacia tree and the Acacia ants. While many aspects of this relationship have been studied, we questioned what the extent of this relationship was, specifically what conditions could impact ants’ behaviors of defense. We asked how defense response time of Pseudomyrmex spinicola varies in relation to different temperatures throughout the day. We hypothesized that the response time to a threat would lengthen as temperature increases, likely due to the ants’ preference to conserve energy during hotter temperatures. To test this, we sampled 30 different Acacia trees of species Vachellia collinsii, all similar in stem diameter (0.6-1.5cm), throughout the day: 8 am, 9:30 am, 11 am, 1 pm, 2:30 pm, 5 pm, and 8 pm. To determine response time to an external stimulus, we tapped a branch of the tree with a stick three times measuring the time elapsed from the initial stimulus to the time an ant arrives at the area of impact. The temperature of the thorn the ants come out of was also measured. After running an ANCOVA, we found that ants responded slower to threats in the morning and when temperatures were colder. While these findings did not support our initial hypothesis, they contribute to the idea that external conditions may affect the threshold to which mutualistic relationships are beneficial for contributing species, this being temperature for the Acacia-ant relationship investigated here. With the changing climate, it is possible that these benefits can decline if the changing conditions are outside of a mutualistic threshold.

Study by Nate Bennett, Glen Langan, & Leo Lerner

Future climate models predict that precipitation patterns will drastically change. In the tropical dry forest of Palo Verde, during the dry season, almost all the rainfall happens in an extremely short time. Precipitation models predict either a decrease in average rainfall over the dry season or an increase in the number of severe rainfall events. Our experiment attempts to test the effects of these future predictions by measuring the absorption efficiency of Acanthocerus tetragonus (Pitahaya cactus) given different amounts of simulated rainfall. Twenty individual cacti were sampled, and several measurements were taken to determine size of the plants (base segment diameter, number of segments, and number of stalks). After initial measurements were made, we categorized each plant into treatments (control = no water, treatment 1 = 1 liter, treatment 2 = 2 liters, treatment 3 = 3 liters) with a variety of sizes within each group. We then added water to the plants and recorded the time treatments were added. Every two hours after the water was added, we returned to the plants to measure their pleat depth and soil moisture at the base. Soil moisture and pleat depth served as our measurement of water absorption because the Pitahaya cactus is known to be able to absorb and retain water within its tissues. Measurements were taken four times a day for a total of eight measurements over two days. We found a significant relationship between pleat depth and plant size, although, there was no significant relationships between plant size and the rates of change in either pleat depth or soil moisture. Unexpectedly, within the first two hours the control cacti swelled significantly more than the treatments. The mechanisms of this swelling are still unknown and would be a good subject for further study.

Sophia Kruger measures canopy cover over a pool of the San Miguel River

Study by Sophia Kruger, Logan Goettl, Madison Deile.

With climate change continuing to produce heavy rainfalls and extreme weather events that alter the composition of water sources, water contamination concerns remain. Within the Cabo Blanco Nature Reserve exists a freshwater to saltwater gradient as the San Miguel River flows into the Pacific Ocean, providing an ideal environment for a controlled study on water quality through the analysis of microhabitat bacterial content. Stemming from interest as to how salinity may influence bacterial count, this study questioned how environmental factors affect the bacterial count of eight microhabitats ranging in distance from shore. We hypothesized that microhabitats with greater leaf litter coverage would produce higher bacterial richness and abundance due to additional micronutrients available from decaying organic matter, whereas a higher algal content would produce the opposite in response to competition for sunlight. Also, we anticipated microhabitats of higher salinity would produce lower bacterial richness overall. Across these microhabitats, three BioPaddle samples were taken from water sources and other aquatic surfaces (rocks, alga, and submerged leaves). Percent leaf litter cover, canopy density, algal count, temperature, pH, and salinity were measured across freshwater and marine standing water pools. All samples from the river and tide pools had microbial growth, including Staphylococcus and E. coli. After analyzing the relative bacterial species richness and bacterial abundance on the agar samples in relation to percent leaf litter and percent algal area of the pools, we found that neither richness nor abundance was significantly correlated with either leaf litter coverage or algal cover. Additionally, the relationship between bacterial richness and salinity and richness and canopy density were not statistically significant. However, microbial richness was significantly higher in river habitats compared to tide pools. Also, the amount of microbial growth was higher on the surfaces of rocks and leaves than it was in open water. Further analysis considering other water composition factors and species interactions beyond those of the hypotheses tested has the potential to further explain our findings.

Biopaddles showing growth of Staphylococcus (top) and Pseudomonas (bottom) bacteria from a river sample.

Hermit crabs can be too small for their shell (L), too big for their shell (R), or just right (middle).

Study by Alyssa Risch, Josh Schauer, & Glennon Langan

Prey species have various defense mechanisms against predation, including hiding, fleeing, or fighting. Hermit crabs (Coenobita compressus) are prevalent on the beaches of Cabo Blanco and use the defense mechanism of hiding in their shells. However, these shells do not always fit the crabs that hide within them. In this study, we focused on the effects of hermit crab size, shell fit, and time of day on the amount of time they hid in their shells and the speed at which they escaped the simulated predator attack. We measured mass and claw lenth as proxies for crab size. We also categorized shell fit as small, flush, and large. Lastly, we measured hide times and escape speeds. We discovered an interactive effect between claw size and shell fit on hiding time, with a positive relationship between size and hiding time amongst crabs who were categorized as flush. This could be because crabs that do not fit their shells are less comfortable hiding for long periods of time. We also found a significant interactive effect between time of day and shell fit on hiding time, with crabs with small shell fit hiding longer in the morning than in the afternoon. This could be because in the morning, it is slightly cooler than later in the day, so they are willing to hide longer in their shells with no danger of overheating. Finally, we found no significant relationship between claw size and escape time. Since the shell is so important for hermit crab predation defense, future research could look further into shell characteristics and the tradeoffs of different shells. For now it appears that having a shell that fits just right allows hermit crabs to better gauge the appropriate escape response without having to try out other shells…

Hermit crab and escape arena.

 

Land crabs make burrows under trees (below)

Study by Elizabeth Luotto, Leo Lerner, & Brady Hartman

Nutrient cycling occurs in all environments and plays a key role in the composition of various habitats.  In Cabo Blanco, Costa Rica, nutrients move through multiple ecosystems from the ocean to the tropical dry forest to the atmosphere and back into plants and animals.  Land crabs burrow in this dry forest near the costal areas and contribute to the nutrient cycle in their local environment as soil engineers.  However, they are also known to prey on plant seeds and destroy seedlings affecting the success of plants in their immediate vicinity.  We investigated if the abundant tree species Adenocalymma inundatum nearby to these crab holes uptake more nutrients than those located further away.  To explore this question, we took samples of 30 individuals in the Cabo Blanco forest, both above and below the limestone bluff. Located about 150 meters away from the shoreline, the bluffs separate the forest into two different sections. We found that trees above the bluff had a higher nitrogen content when they were located close to crab burrows with a larger average diameter.  This same relationship was not present in trees below the bluff, or with other measures of crab burrow density such as the number of crab burrows, average distance to crab burrow, or nearest distance to crab burrow.  Soil moisture or canopy cover does not explain the difference in nitrogen content above the bluff.  Future studies should specifically investigate whether crab burrows above the bluff and the nutrient content within the soil near crab burrows are related in order to further explore the role of land crabs in nutrient cycling in the Cabo Blanco forest.

Brady Hartman taking measurements (L). Chlorophyll meter (top) and measuring nitrogen in leaf stems (bottom)

The San Miguel River meets the Pacific Ocean at the Cabo Blanco Absolute Nature Reserve, but the dry season creates barriers to aquatic organisms

Study by Nate Bennett, Mackenzie Korbel, Mary Thelen, & Alex Morrison

In nature, some species can exist within a wide range of habitats that may have extreme conditions. In order to survive in these areas, they must be able to get to the habitat (overcome physical barriers) and the habitats’ conditions must fall within their fundamental niche. A range in habitat conditions can be observed at Cabo Blanco Absolute Reserve where the freshwater San Miguel river meets the Pacific Ocean. During the dry season, small pools of freshwater form in the San Miguel and a sandbar is present, redirecting the flow of the river underground. Specifically, during low-tide, there are both stratified and salt-water pools at the mouth of the river. We investigated how these pools can be characterized by salinity, pH, and temperature, as well as observed how species compositions change and overlap between the three habitats. Using careful observations and water samples we characterized these habitats and identified the different morphospecies within them. We found significant differences in pH, temperature, and salinity between the fresh, mixed, and salt-water pools. Overall, we found 36 different fish and invertebrate species within these pools. While freshwater and salt-water pools had high numbers of unique species, indicating different fundamental niches, there were only two unique species in mixed pools. Snails and hermit crabs were shared between all three habitats, likely because they were able to overcome the physical barriers between the freshwater and low tide pools. Further studies could aim to determine the extent of these species fundamental niche by investigating species tolerance or abundance during the wet season when no physical barriers are present.

Mary Thelen and Alex Morrison sample aquatic organisms in a freshwater pool

Can ants overcome a DEET blockade of a pheromone trail to reach a reward?

Study by Logan Goettl, Mackenzie Korbel, and Leo Lerner.

Chemicals in the environment are a concern that has been present for years. Many chemicals are being introduced into the environment for anthropogenic purposes, interfering with the chemical communication insects use. All species of ants use pheromone chemical trails for various purposes, such as signaling for food or warning of predators. These pheromone trails are essential for ant communication and the overall success of the colony. Cardiocondyla, a genus of ant under the Myrmicinae subfamily, is abundant around the globe but is relatively understudied. This study investigated how chemicals, particularly DEET, impact ant pheromone trails for food among different locations. We baited ants with 1.0g of damp sugar and after a pheromone trail was established, treatments of 2:1, 1:5, and 1:10 concentrations of OFF Deep Woods 25% DEET to isopropyl alcohol were applied, surrounding the food. Ant travel rate was used as a metric for the impact of DEET. We predicted that higher concentrations of DEET would greater reduce the rate of ant entry and for a longer duration. Our results revealed a significant difference in recovery times between highest concentration and lowest concentration, with the higher concentration having a longer recovery time to full trail. Additionally, our results suggested a significant difference in change in average rate among treatments, with highest concentration having the highest change in average rate of entry to sugare. Finally, the patterns of rate of movement were as expected, with decreases in rate shortly after treatment application in all except the control. Since so little is understood about the impact of DEET, these results may be used for greater understanding the physiological effects DEET has on various insects and how pheromone utilizing insects interact with foreign chemicals. Further research studying other species, other insects, or other chemical disruptors may be useful and could greater expand the understanding of human impacts on the environment.

Leo Lerner observes two treatments during an experiment.

A ‘blue-jean frog’ interacts with a model ‘rival’ made by the group. The plastic bag contains a speaker that played a male call.

Study by Nate Bennett, Glennon Langan, and Elizabeth Luotto.

In species with low predation rates, intraspecific competition is often more important to reproductive success and can lead to strong territorial behavior. This behavior is observed in male Oophaga Pumilio, commonly known as the Strawberry Poison Dart Frog, which occupy 2-3 m² breeding areas with high female density. Males can be identified by the chirping they use to defend their territory, an honest signal of their fighting ability. We looked at how the perceived strength, defined as size of the frog and its chirping volume, of a competitor influences the motivation of a defending male to protect their territory. We placed a clay frog model and Bluetooth speaker within another male’s territory and mimicked the call of the frogs. Then, we measured the latency, duration, and number of calls from the defending frog.  We found that 88% of defending frogs approached our model and that 93% vocally responded. A two-way ANOVA showed a significant interactive effect of size of the model frog and call volume on the number of call responses.  Other two-way ANOVAs showed a significant relationship between model size for both latency and call duration. These results suggest that defending male frogs respond more quickly and often to smaller competitors and that size may be a greater motivator than volume. We hypothesize that because vocal calls are an honest signal of fighting ability, they may be sufficient to defend territory when the intruder is small and quiet and suggest this as a future area of research.

Nate Bennett and Elizabeth Luotto (Glennon Langan not pictured) observe interactions between frogs and models (shown on right).

Madison Deile enjoying the abundant peccaries at La Selva Biological Station.

Study by Madison Deile, Alex Morrison, and Josh Schauer.

At the La Selva Biological Station, the Collared Peccary can be widely spotted exploring the grounds. This species is important to the ecosystem of La Selva since they are ecological engineers, due to the depressions they create in the mud. These wallows act as standing ponds and breeding grounds for amphibians and mosquitos. Furthermore, Peccaries are important for seed dispersal of the various trees and plants at La Selva. With this knowledge, we were interested in understanding the behaviors of Peccaries and what drives their behaviors. We asked how sex, weather, and time of day affect the time allocation of Peccaries. We hypothesized that males would spend more time grooming others, all would spend more time resting in rainy weather, and all would spend more time forging in the morning. For our study, we spent three days observing Peccaries in the morning, afternoon, evening. Each of us observed three different Peccaries for 20 minutes or until they disappeared into the treeline. We recorded sex, weather, time of day, and the time spent performing the behaviors. We categorized the behaviors as resting, traveling, foraging, groom others, being groomed, and self-grooming. We found that males spend significantly more time resting and significantly less time foraging than females. Juveniles (which we referred to as pumpkins) were intermediate between adult males and females. In general,foraging and resting were the dominant behaviors for peccaries, and sex was the best predictor for behavior. We found no effect of weather or time of day as we hypothesized. This study is important as it adds to the knowledge base of the species, including behavioral and ecological engineering understanding.

Josh Schauer observes a distant collared peccary.

Study by Brady Hartman, Sophia Kruger, Alyssa Risch, and Mary Thelen.

Both army ants and leaf-cutter ants are prevalent species at La Selva Biological Station in the Caribbean lowland wet forest of Costa Rica. While they differ in their traveling methods and type of nests, they both use pheromone trails to ensure everyone follows the same path. The goal of this study was to determine whether species of ant, width of the ant trail, or flux of ants moving on the trail was correlated with a faster response time when an obstruction was placed in their path. We found trails of army or leaf-cutter ants and measured the flux in ants per second. We took photos of the trails and calculated the width of the trail using the program ImageJ. We then placed an obstacle in their path and measured the time between placing the obstacle and the re-formation of a fluid path. Our results showed that army ants were significantly faster at responding to the obstacle than leaf-cutter ants. There was no significant relationship between width of the trail and response time. Nonetheless, wider ant trails could lead to stronger pheromone trails, so future research should consider this. There was also a significant interactive effect of species and ant flux on response time. While higher flux of leaf-cutter ants was correlated with quicker response times, potentially due to a stronger pheromone trail, this relationship was much weaker with army ants. Based on our results and army ants’ ability to maintain a consistent response with varying flux, we believe that army ants are more systematic in their travel methods than leaf-cutter ants.

Two Palmito Morado planted at the same time 10 yrs ago.

Study by Leo Lerner, Josh Schauer, and Mary Thelen.

Palmito Morado (Perstoea acuminata) is a palm tree native to the highland forests of Costa Rica. Due to it being almost extirpated from the area, a restoration project in 2010 was started at Cuerici Biological Station. Although all the palms at Cuerici were planted in the same year, they range widely in size. The purpose of this study was to determine the factors that influence the size of Palmito Morado. We expected that palm trees growing in moist, nutrient rich soil with high canopy cover would be larger than palm trees growing in other environments. According to local experts who planted the trees, Palmito Morado prefers moist soil with high nutrient content in shady areas. Seventeen palms were sampled in the study. We recorded height, circumference of the base, and number of fronds as measures of palm size, however palm height was used as the main measure during data analysis. We measured soil moisture, soil nutrient content, canopy cover, and slope aspect of each palm. We ran a multiple regression test to determine if there were significant relationships between the height of the palm trees and their growing conditions. Nutrient content was removed from the model because we found it to be insignificant. We found significant positive relationships between soil moisture and palm height, as well as east-facing slopes and palm height. We found a significant negative relationship between south-facing slopes and palm height. Lastly, we found no significant relationship between canopy cover and palm height. According to our data, we would expect that palms growing in moist soil on east-facing slopes would be taller than palms growing in other conditions. Our data could provide important information on ideal habitat for Palmito Morado in future restoration projects.

Measuring palmitas (from L to R): Josh Schauer, Mary Thelen, and Leo Lerner.

Elizabeth Luotto (L) and Alyssa Risch (R) measure a large bamboo cluster. Alex Morisson not pictured.

Study by Elizabeth Luotto, Alex Morrison, and Alyssa Risch.

In the secondary forest of Cuerici, bamboo appears along the trail in vastly differing sizes, yet they are all the same age due to their cycle of growth, flowering, and simultaneous death.  Alder trees are also found frequently in the secondary forest and are known to have nitrogen-fixing bacteria.  Bamboo are part of the grass family and therefore are nitrogen intensive.  Furthermore, bamboo tend to grow better with better light exposure.  With this information in mind, we looked at multiple factors that might affect bamboo growth, defined as stalk number, cluster diameter, individual stalk diameter, and height.  We hypothesized that greater canopy cover over the bamboo and a greater distance to the nearest alder tree would negatively correlate with bamboo growth.  We also predicted that greater chlorophyll content would correlate with less growth.  To test these hypotheses, we sampled fifteen bamboo clusters in the secondary forest.  We ran a multiple regression for each growth variable and found that stalk number had a significant positive relationship with distance to nearest alder.  We also ran individual linear regressions.  The first regression on the dependent variables of individual stalk diameter and stalk number had a significant positive relationship, and the second showed a significant negative relationship between the two independent variables of chlorophyll content and distance to nearest alder.  These results do not support our hypotheses, as they predict that bamboo stands closer to alder trees will grow less, but have a higher chlorophyll content.  However, the results give information about potential bamboo-alder species interactions which could give insight to future research. We hypothesize that bamboo clusters closer to alder trees may have higher canopy cover, possibly resulting in less sunlight and less growth. The higher chlorophyll content might be due to close proximity to nitrogen-fixing alder. Conversely, clusters further away from alder trees may have lower canopy cover and more sunlight, resulting in more growth.

Artist’s rendition of results from this study.

Mosses are common in the cloud forests of the Talamanca Mountains in Costa Rica.

Study by Mackenzie Korbel, Sophia Kruger, Glennon Langan.

Within the cloud forest, moss serves an important ecological role of retaining water from rain or fog over short and long periods of time. This study investigated how the water capacity and rate of water loss may differ among two moss species, namely the Old Man’s Beard (Barba de Viejo) and Orchatilla, and elevations, high and low. We hypothesized that the amount of water capacity and the rate of water loss would differ significantly between moss species and elevations tested. For example, we predicted that the Old Man’s Beard species at the high elevation would retain the least amount of water initially and lose this water mass at the highest rate.

Seven moss samples of each species were collected from the same approximate location at both the high (9240-9330 ft) and low (8790-8950 ft) elevations. One-gram moss samples were measured, soaked in water for five minutes each, weighed initially for wet mass values, and measured again every thirty-minutes for six hours, then every three hours to complete a twenty-four-hour experimental period. For all twenty-eight samples collected, the rate of water loss and water capacity were measured. The statistical analysis program JMP, was used to compare effects of species and elevation on water capacity and rate for water loss. Overall, the findings concluded that water capacity changed with elevation for the Old Man’s Beard species but was not statistically significant for the Orchatilla moss. Also, the Old Man’s Beard species reported the highest rate of water loss over a short-term period, regardless of elevation. Over a long-term period of twelve hours, the low elevation Old Man’s Beard and high elevation Orchatilla mosses displayed the highest percent of water mass remaining. Given moss tendencies to retain water, issues may arise if lower elevation mosses develop characteristics of higher elevation mosses, as cloud forests continue to recede due to climate change.

Ingenious improvised moss drying rack built by Mackenzie, Sophia, and Glennon.

Madison Deile and Brady Hartman study tradeoffs in epiphytic (left) versus terrestrial (right) Anthurium.

Study by Nate Bennett, Madison Deile, Brady Hartman, and Logan Goettl.

The Anthurium anturio plant is native to the Latin American Cloud Forests and is commonly used for cooking at high elevations in Costa Rica. Anthurium anturio can grow both epiphytically and terrestrially in the region surrounding Cuerici Biological Station. We were curious about how various ecological and biological factors differ between the two behaviors of the plant. We measured chlorophyll content, base stem diameter, total leaf area, leaf number, flower number, canopy cover, and height relative to the forest floor of both epiphytic and terrestrial behaving plants. A total of 72 terrestrial and 68 epiphytic plants were sampled in our study. We predicted all but stem diameter and height would be equal between the two behaviors, and there would be interactive effects between factors. We found epiphytic plants were more prevalent in areas with high canopy density, likely because their height gave them a competitive advantage in capturing sunlight. Additionally, terrestrial plants had a greater stem width than epiphytic plants of similar height. Furthermore, all factors had interactive effects except for number of leaves and canopy density. Lastly, there was not a significant relationship between canopy density and chlorophyll content. This data could be used to further investigate how Anthurium anturio allocate their resources for optimal growth. Future research could account for changes in elevation and age of plants to better explain these energy tradeoffs.

Study conducted by (from L to R) Brady Hartman, Madison Deile, Logan Goettl, and Nate Bennett.

(This post was written by Maggie Schmaltz, a rising sophomore Biology of Global Health major at the University of St. Thomas. Maggie spent June 2019 in Cape Town, South Africa on a course entitled “Urban Agriculture and Social Innovation”)

The scientific community is bad at getting its point across.

Exhibit A: It is common knowledge that ice caps and glaciers are melting as a result of global warming, leading to rising sea levels. But, how bad is that? Well, 11 percent of the world’s population (about 800 million people) live within 33 feet of sea level. Rising oceans may displace many of these coastal residents in the coming century, undermining economies, infrastructure, and ecosystems around the world.

Exhibit B: Most people know that soil erosion is “bad”- but do people know how bad? Desertification across the globe is leading to less arable farmland available to feed an ever-growing population, and the situation is rapidly getting worse. For example, in South Korea, dust storm season is now 118 days per year, up from 39 days per year in the 1980s (Brown LR (2012) Full planet, Empty Plates, pg 50-).

Maggie (the author) planting at an Abalimi farm

An inability to effectively communicate the likely impact of climate change and global resource management is a significant failure of the scientific community. It is hard for people to take difficult steps to address a problem if they don’t understand the impact a lack of such action will have.

(This post was written by Mallory Hedden, a rising senior Biology major at the University of St. Thomas. Mallory spent June 2019 in Cape Town on a course entitled “Urban Agriculture and Social Innovation”)

This June, four students and I have traveled to Cape Town with our professor to study urban agriculture and its links to environmental issues and social inequalities. Cape Town was chosen as our setting because it is still recovering from 50 years of apartheid, and unequal access to food and water are significant issues. During our first week, we had the opportunity to visit two farmer’s markets to help visualize these inequalities. The first was the Oranjezicht City Farmers Market located in the Cape Town waterfront district, a tourist area with restaurants, shops, live music and a Ferris wheel. The second was a farmer’s market in Khayelitsha, a township comprised of informal housing located in the Cape Flats of Cape Town.

We started one Saturday morning off by visiting the Oranjezicht market, which was recently highlighted in the New York Times. This market had one main section dedicated to pastries, cheeses, teas, oils and vinegars, breads, vegetables, and meats, all of which had sample trays for customers to taste the products. Another section of the market was dedicated to plants of all types, along with jewelry and clothes. The back of the market consisted of food stalls where cooks prepared all different cuisines of food for anyone who wanted a hot meal for breakfast or lunch. To top it all off there were adorable puppies being sold for adoption at the entrance of the market. The atmosphere was a bit loud with mostly white touristy people swarming all over the place, but this farmer’s market had something to offer for everyone. Although questionable as to whether it truly qualified as a “farmer’s market”, the Oranjezicht City Farmers Market was impressive nonetheless. The only aspect I struggled with is that it didn’t represent the demographics of Cape Town, which is predominately populated by “Colored” and “Black African” people. The prices were also relatively high, so I got the sense the market was only intended to attract rich tourists.

(Scenes from the Oranjezicht market)

(The post below was written by Sophia Brown, a rising senior Biology major at the University of St. Thomas. Sophia spent June 2019 in Cape Town on a course entitled “Urban Agriculture and Social Innovation”)

Environmental and feminist concerns are intimately connected. It no longer suffices to treat climate change as a scientific problem requiring technological and scientific advances because climate change is not simply a scientific problem. Climate change requires transforming ideologies, exposing exploitation, recognizing colonialism, and ending economic domination. While working on urban farms in townships in Cape Town, South Africa, I noticed most of the farmers were women, specifically black older women. This intrigued me because as I was talking with the farmers, I realized they had unique contributions to farming that no one else could bring.

Sophia (lower left) talking with Babalwa (left), Lizowea (second from right), and students

A few students and I have come to Cape Town to study the biology of urban agriculture. A lot of our time is spent learning about soil preparation, composting, and crop production at urban farms in Khayelitsha, the largest township in South Africa. But we’ve also had opportunities to meet and learn from many different people throughout Cape Town.

I asked the students to describe a memorable conversation or interaction that they’ve had since they’ve been here. They’ve produced a diverse collection of memories. Steven describes an interaction at one of the urban farms in Khayelitsha; Sophia writes about an overnight camping trip in Hottentots Holland Nature Reserve with members of an organization called Usiko dedicated to helping youth at risk; Maggie writes about Faizel, a friend from the Cape Malay community; and Mallory writes about a conversation during a Dine with Khayelitsha event, in which we ate dinner in a shanty with residents. I think the words and pictures will give you at least a sense of these experiences.

Here they are:

STEVEN PLOUFFE: “On our second day at one of the gardens in Khayelitsha our program leader Zack had us do an exercise to initiate communication between the university students and the locals. We were set up in two circles; the university students on the inside and the locals on the outside. Zack then followed to ask us questions in which both the students and the locals spent about 30 seconds going over their response.  One question he asked was: “If you could change one thing about your community what would it be?”  as I was standing across from Mama Babalwa. I answered that I would like to make my community more inclusive as I told her how rarely I interact with my neighbors. Mama Babalwa was absolutely blown away. She then followed to tell me a little bit about how her community works. She told me how everyday her and her neighbors have meaningful down-to-earth conversations. She told me how often they support each other in times of need and how her community was like family. Now I was the one who was blown away. The idea of a community being so interwoven is something completely new to me. Coming into Khayelitsha I never thought I would learn how to improve my community. I figured that since our houses are bigger and our wallets are fuller, we are doing everything right. This could not be further from the truth. I realized after having this conversation that I need to take a step back as to how I look at things. Regardless of status everyone has something to offer and if we fail to acknowledge this we fail to learn.  I am so happy to have had this conversation with Mama Babalwa, and am excited to approach everything with an open mind as this trip continues.“

Mama Babalwa at a farm in Khayelitsha

Five biology students and I have come from the University of St. Thomas (MN) to study “Urban Agriculture and Social Innovation” in Cape Town, South Africa. We are spending June immersing ourselves in the local food system in Cape Town thanks to the leadership of our partner Zach Lager and our support organization, Think Impact.

Our main focus has been to work on community and school gardens in Khayelitsha, the largest and fastest growing township in South Africa. Our host in Khayelitsha, the organization Abalimi Bezakhaya “Farmers of the Home”, works to help urban farmers “supplement their existing, inadequate supply of food and create livelihoods”. The students are learning from the farmers and thinking about potential collaborative projects (here is a video to show what the work is like).

One of the Abalimi Bezakhaya gardens in Khayelitsha

We have also spent time visiting locations and meeting people across the city. We have a great time working with the Muslim Cape Malay community and experiencing the hip scene in the waterfront and cape town business district.

The students generally don’t have a lot of experience in agriculture and they’ve never before been to any place like Cape Town. So they have a lot to learn. But should they just be learning? Or should they be trying to make a difference too?

This June, five students and I from the University of St. Thomas have traveled to Cape Town South Africa to study urban agriculture and the local food system. Our work will weave together several themes, including problems facing global agriculture, challenges and opportunities associated with urbanization (including urban agriculture), and the cultural complexity of Cape Town and (more generally) South Africa.

The students on this course are all biology majors, but they are at different points in their career (sophomores to seniors). None have previously traveled to South Africa or any place similar.

Our first two days were spent trying to familiarize ourselves with the cultural history and current conditions in Cape Town. We realize that we won’t be able to understand the complexities, but we hope that we can learn something that will inform our work back in Minnesota.

To start, we toured a beautiful urban farm, Oranjezicht City Farm, created in 2012 at the site of the Oranjezicht Farmstead that was initially established in the early 1700s. The farmstead was a colonial farm that provisioned ships traveling around the Cape of Good Hope. Today, the farm provides educational experiences, has a thriving CSA program, and supports a wonderful market in the waterfront district.

We also had the opportunity to climb to the top of Lions Head  and visit the District 6 Museum, which is dedicated to the memories of the forced removal of residents during the apartheid era.

Here are some of the students’ reflections on some of their first impressions of Cape Town after these experiences:

Giant red land crabs make burrows in the coastal forest near the ocean, but they have gills and must return to the water to reproduce. How far from the water should they go?

Giant red land crab (Gecarcinus quadratus) are abundant throughout the Pacific coast, and the number of holes from these crabs is known to decrease as the distance from the ocean increases in the Cabo Blanco Absolute Nature Reserve, but the reason for this is not completely understood. We hypothesize that the moisture in the soil and the size of holes made by the crab will increase as distance from the ocean increases. This is because larger crabs, which dig larger holes, will be able to out-compete smaller crabs for preferred habitat and resources. Seven transects of 50 meters parallel to the ocean were measured, and quadrats were established every 10 meters. The number of crab holes were counted and diameter was measured for each hole, and soil moisture was averaged using three measurements per quadrat.

A giant red land crab hole with a pencil for scale. This was one of the largest burrows found.

The abundance of crab holes and hole size were significantly correlated with increasing distance from the ocean. The abundance of crab holes was not significantly correlated with soil moisture, as was soil moisture and distance from the ocean. However, average soil moisture and diameter of holes was found to be significant. This means larger crabs have more energy to allocate to competition for better habitat and resources. These findings have significant implications for the forest. Since trees produce a higher quantity of seeds in response to heightened crab predation, there may be more trees growing further inland than closer to the coast due to the abundance of crab holes. Overall, crab hole abundance and size increased as distance from the ocean increased, but the trend in hole size was likely not due to soil moisture even though there was a correlation between the two factors.

Evan Host and Ryan Anderson (Maddie Guentzel and Mikayla Newby not pictured) make a sampling transect to quantify crab hole abundance.

Dominant tree species in the coastal forest of Cabo Blanco.

There are two general seasons experienced by most tropical forests, wet and dry seasons. During the wet season, all species of trees receive consistent amounts of water through rainfall on a majority of the days. During the dry season inconsistent rainfall leads to water stress for the trees, as less of this resource is readily available. The impacts of this water stress on the different tree species found in the dry forest ecosystem are unknown. Our experiment is to determine how water stress and the dry season impacts tree growth and species diversity. Three transects were formed perpendicular to a freshwater stream in the Cabo Blanco Absolute Nature Reserve. Each of these transects are 60 meters in length, and at every 9 meters along the transect a quadrat of 5 by 3 meters was located. In each quadrat the number of different species present were determined, four soil moisture readings were measured and averaged, while the circumference of the five most prevalent tree species (Hyperbaena tonduzii, Brosimum alicastrum, Pachira quinata, Trichilia martiana, and Calycophyllum candidissimum) were measured at chest height. The results displayed a significant trend indicating that as water stress increases, diversity of tree species decreases. There was also significant trend in the data supporting the decrease in species circumference based upon water stress. The only tree displaying consistent tree circumference measurements was P. quinata, with a constant circumference that was independent of soil moisture. For this data, it can be inferred that P. quinata has adapted to allow the size of the tree to remain constant regardless of whether it is the dry or wet season; for example, these results may be due to root depth, size or amount. This study may be applied to better understanding climate change and the possible impacts on certain tree species as temperatures increase and regular precipitation decreases.

Sean Keup, Jeremy Truong, and Nick Vipond (Elizabeth Mangen not pictured) measure soil moisture and tree species diversity along a transect in the coastal forest of Cabo Blanco.

 

This large hermit crab relies less on safety in numbers than its smaller counterparts.

Within every ecosystem, it is important to study the relationships between predator and prey. One potential way to examine this relationship is through the selfish herd hypothesis, which states that prey species aggregate together in order to reduce the chances of any one individual being eaten by a predator. At the Cabo Blanco Absolute Nature Reserve, we put this hypothesis to the test using aquatic hermit crabs found in tide pools during low tide. Due to a plethora of natural predators and a lack of defensive mechanisms, hermit crabs have to use their surroundings to ensure their own safety. Our research question was investigating whether the depth or size of tide pools affects the aggregation of hermit crabs. Our hypothesis was that smaller hermit crabs would aggregate more in smaller, shallower tide pools. This is because we assumed that because they have both aquatic and aerial predators, the smaller hermit crabs (which have less natural defenses) would move to shallower pools to avoid aquatic predators and clump together to avoid aerial predators. We randomly sampled 21 tidal pools of various sizes and depths during the morning low tide, collecting data on the density, size, and amount of aggregated hermit crabs in each pool. To analyze our data, we ran a nominal logistic test in JMP Pro 13 and found that of our variables tested, only crab size could predict the probability of whether or not hermit crabs would aggregate. However, both density and pool depth had significant interactions when paired with crab size, and so could also predict aggregation of crabs when paired with their sizes (smaller pools with greater density had higher aggregation of small crabs). These results supported our hypothesis, and have larger implications overall. They can be used to further our knowledge of predator-prey interactions, specifically through the selfish-herd hypothesis.

Rachael Heier, Noelle Laske, and Hannah Wallace (Katie Rudd not pictured) measure aspects of a tidal pool where hermit crabs live.

Ethan Just, Mariah Terhaar, Kara Reardon, and Alex Brown hold some hermit crabs whose responses to simulated predators were measured.

In coastal regions, hermit crabs are an important food source for birds, raccoons, coatis, and opossums. When threatened by predators, these crabs will change their path of direction or hide inside their shell for protection and safety. The shells are important for their survival and their effectiveness in evading predators. The angle of approach by predators may also influence the distance at which the hermit crabs react. We expect that as the mass of the hermit crab increases, the reaction distance will increase, representing a better evasion tactic and survival technique. Crabs that can live longer grow to larger sizes because they have evaded predators for longer. Different sized crabs could have different susceptibilities to predators causing them to have different evasion tactics. Furthermore, we expect that a crab approached from the front compared to the side will have a larger reaction distance, while an approach from the back will have a smaller reaction distance that remains constant for all sized crabs. We also hypothesized that these variables will have no interactive effect on the distance at which a crab reacts to an approaching predator. To test these, we approached 186 different crabs of varying masses from either the front, side, or back at approximately equal proportions and recorded their mass and the distance at which they hid or ran away. The direction at which we approached the crabs had a significant effect on the distance at which a crab reacted (p<0.0001), but a crab’s mass did not have a significant effect on the distance (p=0.5529). Therefore, a predator of a crab could take advantage of this weakness in hunting for their prey by opting to attack from behind. Since a crab does not seem to differ its evasion tactics based on its size, we can infer that different sized crabs do not vary in the distance at which they respond to a predator stimulus. It is possible that they also rely on other survival strategies, such as finding and remodeling shells that are strong, but light enough to carry around.

Alex and Mariah use a stick-leaf “bird” predator, while Kara measures response distances and Ethan measures crab size.

Quadrat sampling of aguacatillo seeds and seedlings in the montane cloud forest of Cuerici by Ethan Just and Mikayla Newby (left) and Mikayla and Elizabeth Mangen (right). Not pictured is Maddie Guentzel.

Quetzal birds, Pharomachrus mocinno, are a threated species that live in the cloud forest of Central America. The cloud forest that they depend on continues to decline due to deforestation. Conservation of this altitudinal migrants’ high and low elevation habitats, as well as connecting corridors, are called for. The Ocotea tonduzii, or ‘little avocado’ tree grows in cloud forests and produce fruit, aguacatillo, which are the critical food source for the Quetzal. As the Quetzal species is on the decline, we wish to investigate the fundamental niche of O. tonduzii as a means by which to restore and protect the Quetzal species. The methods used in determining the location of the fundamental niche included the investigation of seven sites within a canyon region where the O. tonduzii were observed to grow. Four sites were positioned outside of the visible canyon region and three were positioned around the canyon edge. Each of the sites span 100 feet and included 10 quadrants spaced at 10 feet apart. The environment variables measured and recorded at each site and within each quadrant were nitrogen and moisture levels of the soil as well as light and canopy coverage. The number of seeds, saplings, and mature trees were also collected. It was determined with logistic regression that soil moisture had the greatest significance in determining the probability of locating a seed or sapling for a given area. Canopy coverage was another significant factor in determining the location of seeds. These results give insight to the viability of O. tonduzii, which may assist in understanding possible prevention methods for the decline of Quetzal birds.

A Resplendent Quetzal. Yes, we were lucky enough to see one in the dry season – just not this one. (Photograph by imageBROKER/Alamy Stock Photo)

Kara Reardon (barely shown), Jeremy Truong, Rachael Heier, and Evan Host (being held up) measure chlorophyll content in ferns near a trout pond.

A naturally run trout farm located at the Cuerici Biological Station doesn’t use chemicals, and utilizes a naturally flowing stream on the mountain side. In light of this, we decided to use it as a proxy for a natural stream ecosystem in order to test the effects the trout have on the surrounding ecosystem by measuring nutrient levels in the soil and water, chlorophyll levels of nearby ferns, and bug diversity at different sites along the trout farm. We hypothesized that there would be more phosphate and nitrate present downstream of the farm and that these increased levels would lead to more bug diversity and higher chlorophyll levels respectively. We collected chlorophyll levels of ferns at three different sites, upstream of the farm, at fish ponds on the farm and downstream of the farm. We also took soil samples from each of the ferns sampled, and collected bugs from both the upstream and downstream locations. Our findings showed a significant increase in chlorophyll levels and increased bug diversity, measured by richness and evenness, as we moved downstream. However, our levels of phosphate and nitrate in the soil did not show significant correlation with increased chlorophyll levels and higher bug diversity. Further tests of soil nutrients and canopy coverage also did not show significant correlation with our results. Therefore, increased chlorophyll and bug diversity could be influenced by other factors such as the soil type, surrounding flora, and other present nutrients, possibly from fish excretions. While certain limitations prevent us from generalizing our findings (only tested one trout farm, only tested certain species of flora, etc.), our findings still show us that the trout farm most likely has some sort of effect on this stream ecosystem, and that as a proxy, this experiment shows us that a similar natural stream ecosystem could have higher chlorophyll levels and greater bug diversity downstream of where trout are present.

A clump of vegetation, including ferns measured, along a stream that supplies a trout farm in Cuerici.

Sean Keup and Hannah Wallace (shown) collect leaf litter and invertebrates in the montane cloud forests of Cuerici in Costa Rica. Not shown from their group are Alex Brown and Nick Vipond.

This study examined at how these three factors (soil moisture, leaf litter mass, and canopy cover) affect insect and invertebrate biodiversity at the Cuerici Biological Station in Costa Rica. It was hypothesized in this study that higher canopy cover, higher soil moisture, and higher leaf litter mass would contribute to a higher insect/invertebrate abundance and diversity. There were thirteen different sites in Cuerici where the sampling took place, each below the transition tree line elevation (2800 meters). At each of these sites, soil moisture content, leaf litter mass, and canopy cover were all measured. The leaf litter samples were taken back to the station. The samples were then massed, and the insects and invertebrates were then removed and examined for abundance and diversity of species. The results indicate that the only significant independent variable that influenced invertebrate abundance was leaf litter mass, with a positive relationship (P=.0309). The results also indicated that there was no significant correlation between the independent variables and species abundance or diversity. Despite these results, the abundance and diversity can provide insight as to the invertebrate communities of the Cuerici site.

Katie Rudd, Ryan Anderson, Mariah Terhaar, and Noelle Laske measure a nightshade tree and count the number of berries it has produced. This was at our second site, Cuerici/Cerro de la Muerte in a montane cloud forest.

The cost-benefit analysis states that a plant or organism must allocate their resources in a way that is energy efficient while still optimizing essential processes throughout their lifetime. The energy that plants gain is used for two main processes: growth and reproduction. Berry producing plants in particular rely on bird predation of their berries in order to distribute the seed inside. Night shade trees, due to their toxicity to some mammal species, rely entirely on bird dispersal for reproduction. To attract birds, these plants must determine how much sugar to allocate in berry production to maximize reproduction without wasting energy that could be used for growth. Therefore, there is a threshold value when it comes to the optimal sugar percentage. To further explore this concept, we examined the berry abundance and percent sugar content per berry of night shade trees of varying heights and trunk areas. It was hypothesized that as the tree height and trunk area increases, the number of berries would increase significantly. We also hypothesized that as tree height and trunk area increases, the percent sugar per berry would increase significantly until reaching their threshold. A larger is more likely able to obtain more nutrients to produce a larger amount of berries with a higher sugar concentration can focus more on reproduction than growth. Smaller trees are more likely to produce less berries with lower percent sugar because most of their energy is dedicated to maximizing their growth. To test our hypotheses, we examined the number of berries, trunk area, and percent sugar per berry among 10 trees of varying heights. After counting every individual berry on the tree, 15 berries were selected at random and split into groups of 3 and run through a digital refractometer with the average percent sugar content recorded at the end. Circumference and height were measured manually. The collected data was run through several bivariate linear regression models using JMP Pro 13 software. It was determined that our original hypothesis was partially correct, with the number of berries significantly increasing as tree height and trunk area increased. However, the percent sugar content per berry among trees of varying sizes remained relatively constant and showed no significant correlation. Regardless of tree size, we determined that berries will have consistent amounts of sugar. Once a tree has matured enough to dedicate nutrients towards reproduction, it will produce as many berries, each with this set amount of sugar, that is feasible for its size. This experiment gave us insight into the trade-off between reproduction and growth for night shade plants, with our methods applicable to other fruiting species of plants and research on their tradeoffs.

Improvised field equipment and lab space was the norm in the remote cloud forests of Cuerici.

 

Howler monkey troops are common (and quite loud!) at La Selva Biological Station in the lowland rainforest of Costa Rica.

Alouatta palliata, commonly known as howler monkeys, are the predominant monkey species at La Selva Biological Station, Costa Rica. These monkeys make a series of long calls as a means of inter- and intra-troop communication. The loudest calls, which may be heard from up to 1 mile away, have been found to be associated with inter-troop communication. This communication is found to prevent inter-troop conflicts through the determination of neighboring troop locations. We hypothesized that the larger the troop, the greater number of males, and the greater number of juveniles, the greater the number of inter-troop calls. The methods used include observing A. palliata troops in the canopy, recording the number of A. palliata per troop. The gender and relative age is determined through observation, once a single troop is located. The number of inter-troop calls produced in a 10-minute period was counted and recorded. The data analysis was conducted, using JMP Pro 13 software, to generate a linear regression model. The results displayed a significant positive correlation between the number of inter-troop calls and troop size, number of males, and number of juveniles within a troop. There was no correlation between the interaction of troop size and number of males. The results suggest that the number of inter-group calls produced is positively influenced by the size and overall make up of an A. palliata troop. Therefore, this suggests that a larger troop utilizes inter-troop calls in order to maintain a dominant position and to establish themselves as a strong contender for necessary resources and protection of vulnerable troop members as well as the entirety of the troop.

Elizabeth Mangen and Evan Host (left) watch a troop of howler monkeys in the forest, while Alex Brown and Katie Rudd (right) watch a troop near the soccer fields at La Selva Biological Station.

Sean Keup, Mikayla Newby, Mariah Terhaar, and Rachael Heier make observations of hummingbirds visiting flowers of different color, size, sugar content, and species.

Rufous-tailed hummingbirds have been observed throughout La Selva Biological Station and are important for the pollination of flowering plants. This experiment questioned the hummingbird’s preference on color of flowers, species of plants, and volume of nectar. We predicted that the hummingbirds are attracted to the red flowers over the purple flowers. Hummingbirds have vision that  includes UV, which causes ‘brighter’ colors to stand out more. We also predicted that hummingbirds would prefer the larger species of flower, Heliconia pogonantha, due to the greater nectar volume within the flowers when compared to the other two species, Stachutarpheta frantzii and Hamelia patens. Data was collected through periods of observation at a distance of 5 meters from the flowers. In this study, hummingbird preference is represented by the time (in seconds) spent feeding at the flowers and the number of visits to each plant. Data was recorded at two different sites within La Selva. The site at the dining hall contained Stachutarpheta frantzii and Hamelia patens while the site near the gardens contained Stachutarpheta frantzii and Heliconia pogonantha. A two-way ANOVA was conducted on the amount of time spent per visit at each of these species. The results showed that there is a statistical difference in the amount of time spent per visit between the species. Further analyses showed that the flowers who are statistically different from each other are the Heliconia pogonantha and the Stachutarpheta frantzii (P=.0041). A chi-square distribution test was conducted to test if there was hummingbird preference of flower species in number of visits to each plant. This determined that there was a preference of the hummingbird for specific species of flower. We ran a one-way ANOVA for the color of the flowers vs. time spent per visit and found that the hummingbirds spent significantly more time at red flowers than purple flowers (P=0.0029). We ran a one-way ANOVA for nectar volume of the flowers vs. time spent per visit and found that the hummingbirds spent significantly more time on flowers with high nectar volume than on flowers with low nectar volume (P=0.0011). Overall, hummingbirds preferred red flowers, a larger nectar volume, and the flower species Heliconia pogonantha, which is both red and has a large nectar volume.

Rufous-tailed hummingbirds are common at La Selva Biological Station in the lowland tropical rainforest of Costa Rica.

Hannah Wallace, Ethan Just, Ryan Anderson, and Kara Reardon measure the height of some very tall palm trees, using improvised devices where necessary.

Socratea exorrhiza is a species of canopy palm that is commonly found in La Selva Biological Station in a neotropical rainforest of northeast Costa Rica. These palms, along with less commonly found Iriartea deltoidea, have stilted roots that stick up above the ground, which is what gives them their more colloquial name: “walking palms.” The functions of these roots have not been proven, yet it has been hypothesized that these roots allow the trees to move away from disturbances near their germination sites or towards more nutrient rich soils, hence the name walking. We tested a further hypothesis that the roots allow the palms to have a stronger mechanical structure, and grow taller with a more slender trunk. Different heights for both types of walking palms and for other palms, Welfia regia and Prestoea decurrens, were recorded using trigonometry as well as their trunk circumferences. We compared their regressions using an ANCOVA test and found that for any given trunk circumference, the palms with stilted roots on average grew significantly taller than other palms. Therefore, our findings support the hypothesis that stilted roots allow canopy palms to surpass theoretical height limits with skinnier trunks, get more sun exposure, and thrive in neotropical rainforest conditions.

Stilts at the base of “walking palms” gives better stability so that they can grow taller with a smaller trunk diameter.

Maddie Guentzel, Jeremy Truong, Noelle Laske, and Nick Vipond hold “Cherry” the snake, which was used to determine if frogs call less in the presence of a simulated predator.

Previous studies of Strawberry Poison Dart Frog (Oophaga pumilio) communications have shown they call for a variety of reasons, mainly for territorial defenses and mating. Our group was interested in looking at the differential variations in calls of these Strawberry Dart Frogs depending on the time of day and the surroundings. These frogs are diurnal and have one known predator, the night ground snake Liophis epinephelus, which has evolved an immunity to the toxins and is nocturnal. It was hypothesized that the frequency of the frog calls would be higher in the daytime and lower during the nighttime because these animals are most active during the day when other frogs are active. Likewise, it was also hypothesized that their calls would increase in response to a stimulated call and would decrease in response to a perceived predator when compared to baseline values. This was assumed to be the case in our hypothesis because they are territorial towards other frogs and would stay quieter in the presence of predators to protect themselves. An experiment was set-up in which the frequency of calls were recorded at various times throughout the day, with three trials of simulated (i.e., frog) calls and simulated snake movements during each time period. The results show that both the time of day (F_3,87=4.99, P= .0036) and the treatment type (F_1,87=33.23, P<.0001) had a significant impact of frog call frequencies. The interaction between the two variables (F_3,87=2.22, P=.095) or the days the trials were performed (F_1,87=1.46, P=.23) did not show any significance. These results indicate that frogs are the least active at sunrise compared to other times in the day, and were more responsive to the stimulated frog calls and less responsive to simulated snake movements compared to baseline values. These results can give insights to communication patterns of these poison dart frogs. It can also implicate their sleep patterns may be different from being a strictly diurnal animal, as it was active at night to other calls of nearby frogs and least active early in the morning.

This is a reflection written by student Mariah Terhaar as part of BIOL 211 – Introduction to Field Research in Costa Rica. Reflections were written after spending a day exploring cultural sites in San Jose, the capital of Costa Rica.

Beep! Beep! Beep! These are the sounds of an angry motorcyclist trying to cross the road while a group of nine American girls blocks his path. Unfortunately, I was included in this group. Navigating the streets of San José was only the beginning to our crazy day. As we walked out the doors of the Parks Inn Hotel at 8:00 in the morning, we became fully immersed into the lively Costa Rican culture. Our destination was the San José Central Market, which is the largest market located in the city (pictured above). By some miracle, we all arrived at the market in one piece. Walking into the building, we were bombarded by smells of fresh cut flowers and authentic Costa Rican cuisine. Around every corner, new sights, sounds, and smells caught our attention. There were hundreds of shops packed into the building with each one being slightly different. Numerous types of meats, fruits, coffees, authentic meals, and vegetables were for sale, along with other products including local handcrafts, flowers, shoes, and souvenirs. It was easy to become lost in the maze of vendors. Walking around the alleys of over 200 shops, it appeared to be a bustling business. However, if you looked closer, the intricate details became apparent. By observing the leather goods, food, local handcrafts, and plants, I was able to understand how the natural world is reflected in these particular aspects of their culture.

One product in the market that could not go unnoticed were the shoes. Smells of leather surrounded me as I would pass these shops. The shoes that were sold by the vendors were made from genuine leather that had been handcrafted by shoemakers. Leather typically is created from the skin of animals, including cattle and sheep which are both found in Costa Rica. I am uncertain if the leather used to produce the shoes sold at the market were local. However, it is very possible. Also, some shoes had beads and bright colored designs. These designs brought out the colorful culture of Costa Rica with colors of red, orange, yellow, pink, green, and blue. Along with the shoes, there were other leather goods including belts and wallets. When walking past the shops in the market, one might just walk by the shoes thinking nothing of it. However, upon closer inspection, the hidden connections can be understood.

If rice and beans are not appealing to you, Costa Rica may not be the place to visit. Meals in this country typically include a combination of rice and black beans along with various meats and locally grown fruits and vegetables. In the Central Market in San José, these authentic meals could be found. While walking around the market, I spotted many different shops that displayed the range of foods found in Costa Rica. In one shop, fresh fruit was being sold including grapes, mangos, bananas, pears, kiwis, and peaches. Also, more exotic fruits including the carambola, granadilla, and guayaba were found. Vegetables were also sold in the market. These included yucca, chayote, and plantains. A variety of fresh meat was also available at the market. Fish, pork, beef, chicken, and shrimp were common meats sold. Many of these products including fruits, vegetables, and meats are used in typical Costa Rican meals. For example, a casado is a dish that includes rice with a side of black beans, a vegetable like fried plantains, and a meat like chicken. It is amazing to see how the natural products of the land in Costa Rica have sustained the people living there and contributed to their culture.

Many vendors at the Central Market had hand crafted products including wood carvings, painted cups, and dolls. While walking through the shops, I found a store that sold these beautiful products. Shown to the right is one of the painted cups that was for sale. Talking with the shop owner, she explained to me that the cup had been painted locally and was inspired by the native animals of Costa Rica. On the cup is a painting of a toucan on a certain type of tree with pink flowers. Native species such as the toucan are used in various forms of Costa Rican art. This product highlights how the natural world impacts culture. Also, at a nearby shop there were intricate, hand crafted dolls for sale (pictured on the left). These dolls were carrying baskets full of coffee beans and fresh fruit. Fruit and coffee beans are locally produced in Costa Rica. This again is an example of how the environment impacts society by influencing the products they create. Plants and organisms from the environment have impacted the culture which can be seen in their art forms.

Costa Rica is filled with natural beauty. The country has diverse species of plants including flowers of every color in the rainbow. Many of these native flowers can be found at the Central Market. My nose was filled with wonderful aromas as I walked down the aisles by the flower shops. These flowers could be bought to brighten up your home or to give to a loved one. The flowers also inspired artwork, which can again be seen in the painted cup discussed in the previous paragraph. The cup had a native tree called the Roble de Sabana painted on it. This shows how the native plants in the ecosystem have impacted the art in Costa Rican society.

Many individuals travel to Costa Rica and stay in beautiful beach resorts. However, they miss so much. By going to Central Market on Avenida Central, I was able to immerse myself into the Costa Rican culture. Throughout the day, I experienced Costa Rica first hand. I was able to see past a product’s first looks and understand where it came from and how it is related to the Costa Rican culture. Observing the leather goods, foods, local handcrafts, and plants allowed me to appreciate how the natural world is reflected in these particular aspects of their culture.

Flowers are blooming all over the UST campus, and anyone who pauses for a second will notice that they are full of interesting arthropods–from lumbering bumble bees to scores of honeybees (especially on North Campus!), to tiny black native bees (especially on South Campus!), flies that mimic bees, various butterflies, and even a bizarre-looking hummingbird moth–these are just the creatures that we observed during a few walks last week.

Native bees are abundant at the UST Stewardship Garden on South Campus.

These pollinators are economically and ecologically important, and have been under pressure from a combination of habitat loss, pesticides, and pathogens.  Last semester, a team of students in my Environmental Problem Solving class worked on a project focused on pollinator gardens for the Mississippi Watershed Management Organization (MWMO), through the UST’s new Sustainable Communities Partnership program.  MWMO provides funding for the creation of new pollinator gardens for a large portion of Minneapolis, and they wanted to know whether the spatial configuration of these pollinator gardens matters for bees.  We hypothesized that residents in more affluent neighborhoods would be more likely to establish pollinator gardens, and that, as a result, there could be gaps of high-quality habitat in portions of the city–effectively pollinator desserts.  We learned that, while the foraging range of the honeybee (an introduced species from Europe) can extend beyond four miles, bumble bees and other native bees have much smaller foraging ranges, typically less than a half-mile.  Thus, we predicted, in areas were pollinator gardens are sparsely distributed, some of these native species should drop out, thus decreasing bee diversity. The team’s report for MWMO is available here.

A map of all 145 registered honeybee hives (yellow circles) in Minneapolis and Saint Paul.  Honeybees are known to outcompete native bees, so we are interested in how proximity to honeybee hives affects native bee abundance in the Twin Cities.

One of the team members, Brittany Allen, decided to test this hypothesis as a summer research project.  We identified two focal sites at which she will conduct regular bee surveys throughout the summer.  The Urban Flower Field, in downtown Saint Paul (corner of 10th and Roberts Streets) is fairly isolated from other pollinator foraging areas.  By contrast, the pollinator habitat surrounding the UST Stewardship Garden on South Campus is in an area where pollinator gardens are relatively abundant.  Brittany will be making surveys at a number of other locations, and also enlisting the public in our study.  In addition to our question about the density of pollinator habitat, we are also interested in looking at how the proximity of a garden to a honeybee hive affects native bee abundance, as honeybees are known to outcompete native bees.  We are looking for anyone interested in learning rudimentary bee identification and surveying a pollinator garden in their yard or at a public park three times over the course of the summer.  Full details are available here. We’ll be providing updates over the course of the summer.

 

 

 

 

 

Our last batch of abstracts for the 2016 Introduction to Field Ecology course in Costa Rica. This time, the students worked on projects in Tortuguero National Park, one of the most remote parks in Costa Rica (you can only get here by boat or plane). Despite its remoteness, it is the third most visited park in Costa Rica. It was tough to access pristine areas here, so students had to do their best to come up with projects on the finger of land that supports most of the tourist lodges. As always, they came up with ideas, developed the project, collected data, and summarized their results. Here are abstracts from their work:

Isn’t that bird extinct? The potential effect of the pet trade on an endangered species, the Great Green Macaw

Nick Hable, Evan Keil, Sara Osborne

Tropical birds are an important component of the multi-billion dollar exotic pet trade, with 250,000 parrots exported from the tropics annually.  The endangered Great Green Macaw (Ara ambiguus) exemplifies the ecological impacts of the tropical bird trade; the population of this species has decreased 90% since the early 20^th century, and it is now found in only 10% of its original range.  We examined behavioral characteristics of the Great Green Macaw at Tortuguero National Park in Costa Rica, where the species is still abundant, in order to assess the suitability of this species as a pet.  We also collected opinions by local residents and eco-tourists regarding the ethics of keeping macaws in captivity, in order to assess how living in proximity to these birds affects views on this issue.  Because captive macaws are often kept alone, we assessed how often wild Great Green Macaws are found in groups of two or more.  Over three days of observations, all 33 macaws observed were found in groups (p<0.001).  Additionally, 42% of calls received a response.  None of the ten residents interviewed felt that macaws should be kept as pets, whereas two of ten eco-tourists felt that it was acceptable to keep macaws in captivity (p=0.08, R² = .230).  These interviews suggest that there is little support for keeping captive macaws, although this opinion seems to be held more strongly by residents.  Our behavioral observations suggest that macaws are not suited to captivity as they are naturally gregarious.  We suggest that promoting conservation through increased regulation on the exotic pet trade, in combination with habitat restoration, to protect and restore populations of the Great Green Macaw.

Do birds of a feather, actually flock together: Niche partitioning and species interaction in a tropical island marsh

Zach George, Ethan Ridgewell, Jenny Walz, Quinn Whiting

Jenny and Quinn

Yellow-crowned night heron

Costa Rica contains some of the most biodiverse ecosystems in the world. In this study, we explored mechanisms allowing diverse species to coexist. Niche partitioning is the process by which species divide a habitat through the use of varying microhabitats, eating different diets, and/or occupying a location at different times. Many species use niche partitioning to maintain biodiversity in constrained conditions. Tortuguero, Costa Rica contains a hyper diverse bird community, making it an optimal site to study mechanisms that help maintain diversity. This study aimed to determine how the niche is partitioned among this diverse assemblage of birds. We observed bird activity on a small island marsh saturated with different bird species to test three hypotheses: (1) different species will prefer different microhabitats within the island marsh, (2) only one species will occupy a certain microhabitat at a time, and (3) species will use different microhabitats for different purposes. For each bird observed, we recorded species type, location, time of day, and amount of time spent foraging during a five minute observational period. Results indicated that preferred locations differed among species (X²=166.5, df=32, p=0.001,). More than one species may occupy a habitat at one time, negating our second hypothesis (X²=015.8030, df=9, p=0.0001).  In fact, each microhabitat has an equal probability to contain one or more species at a time (X²=13.1562, df=9, p=0.1557). Location does have a significant effect on the average time spent foraging, where birds located in mud and water spent twice as much time foraging than birds located in grass, logs or bushes (F=11.025, df=4, p=0.0001). Though our hypothesis that only one species will occupy at a certain microhabitat at one time was rejected, resource partitioning may be occurring in a different way than spatial or temporal separation. Instead, location did have a significant effect on foraging time, suggesting that the bird species may forage at different times, or in different areas, therefore reducing interspecific competition. Differing diets may be another way these birds partition the niche, as many of the species observed prefer different food sources. A better understanding of niche partitioning in this system may help in the development of conservation strategies in the face of habitat loss caused by human development.

Energy efficiency exhibited by brown pelican (Pelecanus occidentalis) flight patterns

Brennan Arendt, Jessica Brown, Zach Mader, McKenna Reid

McKenna, Jess, Zach, and Brennan

Foraging strategies can vary widely in energetic costs, ranging from sit-and-wait predators with minimal costs, to predators that expend significant energy in actively pursue prey. Among actively foraging species, behavioral modifications that reduce energy expenditures should be favored.  We examined the flight behavior of the Brown Pelican (Pelicanus occidentalis), a species known to forage over tens of kilometers, in response to wind direction and estimated wind speed. We observed brown pelicans over two days in Tortuguero Beach, Costa Rica, under a range of weather conditions, and we recorded the number of wing flaps per 30 seconds as an indicator of energy expenditure, for birds at different positions in flocks. We found no difference in number of wing flaps based on position within flocks.  However, wing flaps increased with wind speed (p<0.001), and we found a significant interaction between wind speed and wind direction relative to pelican flight on number of wing flaps (F_5,88=10.21,p<0.001, r²=0.36). Specifically, wing flap frequency was low and constant across estimated wind speeds from 0-30 km per hour when pelicans were flying with or against the wind, but flapping frequency increased sharply with wind speed when pelicans were flying perpendicular to the wind.  Pelicans were frequently observed travelling in both directions along the north-south shoreline, but we observed no pelicans flying when wind was blowing from the east at  >10 kilometers per hour, suggesting that the extra energetic costs of foraging under these conditions may have exceeded benefits of foraging under these conditions. Our results are consistent with our hypothesis that this actively foraging species modifies its behavior to minimize energetic costs associated with foraging.

Almond Joy and Coco Loco: Testing the Janzen-Connell Hypothesis along the Ocean Shoreline

Katie Hoffmann, Madison Gonsior, Emma Squires-Sperling

Katie and Madison

The Costa Rican rainforest is known for its diversity of trees, insects, birds and other taxa. But why does this diversity exist? One proposed explanation is known as the Janzen-Connell hypothesis. It predicts 1) there will be more seeds closer to the base of a parent tree (due to limited seed dispersal), but 2) there will be more seed predation closer to the parent tree (due to the effects of specialized seed predators). It follows from these two predictions that seedlings will be most successful at some intermediate distance away from host trees. This necessary spacing between members of the same species provides opportunities for other species, and thus contributes to forest diversity. This hypothesis has been generally supported with tests in high-density, high-diversity forests. Here, we tested whether it would similarly apply in a low diversity environment in Tortuguero National Park on the Atlantic coast of northern Costa Rica. We studied the coconut palm (Cocos nucifera) and the almond tree (Terminalia catappa), two common species along the ocean shore. Predators of the coconut and almond seeds include insects making colonies and marks on the seeds and fungi growing within the seeds. We measured the size, total number, and number of predated seeds in the middle of the parent tree’s crown (near) and 5m outside the crown (away). As predicted by the Janzen-Connell hypothesis, seed density was significantly higher near than away from the parent tree (almond: t=-2.921, DF=14.06, P = 0.005; coconut: t=-1.921; DF=15.66, P = 0.037), and, for almond trees, likelihood of seed predation was also significantly higher near the parent tree than away from it (X²=46.995; DF=2; P < 0.001). In contrast to the Janzen Connell prediction, likelihood of seed predation did not depend on location for coconuts (X²=0.191; DF=1; P =0.6617). In addition, we found that almond (t=-2.921; DF=14.06; P=0.0056) and coconut (t=-1.921; DF=15.66; P=0.0366) seeds closer to the parent tree were smaller than those farther away, and the likelihood of predation was greater for smaller than for larger almonds (t=-1.583; DF=596.1; P=0.0570) (seed size did not affect likelihood of predation in coconuts (t=2.165; DF=23.09; P=0.9795). These results suggest that the Janzen-Connell hypothesis was generally supported for the almond tree but not for the coconut tree. The lack of support in coconuts could be due to the fact that there seeds have a very hard outer layer that prevents most seed predation. Predation plays an important role with maintaining equilibrium within the environment. If disturbed, it can lead to imbalance of the populations of many species, therefore affecting the biodiversity of an ecosystem. Understanding how predation effects seed dispersal is important for the preservation and restoration of crucial seed species that support whole ecosystems.

As a preface to today’s post, I head today that eminent Harvard ecologist Richard Levins had passed away at age 85.  Levins began his career as a farmer in Puerto Rico before going on to become a leader in the fields of ecology, biomathematics, and the philosophy of science.  He made this observation in an interview last year: “Biology has become molecular biology and graduates are less likely to tramp through a forest or sniff the earth.  They may not even know anything about the animals they study, just the tissue extract.  So throughout my career I have encouraged students to look at such things as connections between human activity and forests, and changes in human population and agriculture.”  After nearly a month of tramping through forests in Costa Rica, I can attest that our students now know quite a bit about the animals they study, and how humans systems interact with these natural ecosystems.  Perhaps our course, then, is a fitting tribute to Professor Levins.

It’s not easy to get to Tortuguero.  Boarding the bus in Guapiles, we pass through miles of banana plantation with familiar corporate logos—Dole, Chiquita, Del Monte.  We weave through the busy streets of Cariari, and then inch along a pothole-strewn dirt road for another long hour.  This road mercifully ends at a small dock on the Rio Suerte—the lucky river.  Here we climb aboard a boat piloted by Juan Carlos behind the wheel, and his assistant on the bow with a long pole.  We move slowly down the river, as the water level is low in the dry season.   Sand bars and floating trees, together with the swift current, test the skills of our captain.  We pause to observe a crocodile, laying motionless on the muddy bank as the wake from our boat washes over the tip of its long snout.  Eventually the river widens, Juan Carlos pushes the throttle, and the farmland turns into solid forest.  We come to an intersection of sorts.  Juan Carlos points to the right—“Three hours this way to Puerto Limon” he explains in Spanish.  He points left.  “Two hours this way to Nicaragua.”  We go straight, pass a surprisingly steep hill and the tiny village of San Francisco (where you can tie your boat up to the grocery store).  Around one more bend is the seaside village of Tortuguero, perched on a peninsula 29 kilometers long and only about 200 meters wide.

Tortuguero means “Land of Turtles”, and this stretch of beach is the prime nesting ground for the green sea turtle (~20,000 nests per year!), and is also used by leatherback, hawksbill, and loggerhead sea turtles.  Well into the 20th Century, its human inhabitants made their living hunting turtles and jaguars.  Logging companies came in an cleared most of the forest in the 1950’s–the rusting remains of this equipment is still displayed prominently in the village.  Around this time, Dr. Archie Carr discovered the importance of this beach for Atlantic sea turtle populations, and eventually persuaded the Costa Rican government to create the nation’s first national park at this site.  Today the village’s economy is supported almost exclusively from eco-tourism.

Here are some of our students’ impressions of this unique place:

We were all very excited to reach our final destination of the trip; we were excited to be on the beach and finish one last big project for the class. However, Tortuguero has been so much more than any of us expected. We were given a tour around town and the national park by a man named Luis. We were all impressed by his pride in his home and his job. As we spent more time in town we saw that everyone was very environmentally conscious as well as helpful to us throughout our time spent here. We have finally realized that Tortuguero is more than just beach and sun, but about a truly beautiful place along with a people that is committed to keeping it beautiful.

-Brennan Arendt

 

 

Tortuguero is not easy to reach by any means, but the destination is well worth the journey. Arriving by boat, one can see several species of animals such as crocodiles, iguanas, basilisks, and even the endangered Great Green Macaw before they set foot in Tortuguero. The village itself thrives on ecotourism, and this can be seen while venturing through the city and passing various souvenir shops that are run from many local’s homes. Tortuguero Village prides itself on the conservation of many endangered animals, and they do an excellent job of promoting this conservation through various methods such as the Tortuguero National Park.

-Nick Hable

The BIOL 211: Introduction to Field Ecology course is finished at our second site, the La Selva Biological Station. La Selva is one of the most important biological research stations in the New World tropics. Our students spent four days here. As always, they had to come up with a project idea, collect data, analyze their results, and present their findings to the group. It’s intense and demanding, but once again they’ve come up with new and exciting scientific findings. Their project abstracts and pictures are below:

Ch-Ch-Ch-Ch-Chit Chat:  Strawberry “Blue Jean” Poison Dart Frogs respond to a wide range of call frequencies  

Evan Keil, Ethan Ridgewell, McKenna Reid, Emma Squires-Sperling

Oophaga pumilio, the strawberry “blue jeans” poison dart frog, is one of the most striking amphibians in the New World tropics. These frogs use bright red and blue coloration to warn predators of their toxicity. They also chirp at specific frequencies and duration to attract mates and warn or intimidate rival males. Chirp frequency within calls might advertise a male’s quality if higher frequency calls are more costly to produce. Here, we tested whether chirp frequency influences other males’ response call time and duration. We also tested whether response differences were associated with male color intensity. We predicted that individuals will respond more often, more quickly and for a longer duration to faster frequency calls because these calls would signal more dominant (and thus more threatening) rivals. Alternatively, males could simply respond to a species-specific frequency and ignore other chirp frequencies. We also predicted that individuals with brighter coloration will have a shorter response time and a longer duration of their response. We conducted this study at La Selva Biological Station, Costa Rica over two days. We first created calls at three different frequency (slow = .75, normal = 1, fast = 1.25) using the Wavepad app to manipulate downloaded calls. Once a frog was found, we played calls at each frequency in random order. After each call, we recorded whether a frog responded, the time it took to respond (response time) and the duration of the response. We also recorded the brightness of the caller’s coloration. We found that males were equally likely to respond to each call frequency (DF = 2, P = 0.3581), and neither response time (F = 0.2596, DF = 2, P = 0.7730) nor response duration (F = 1.2036, DF = 2, P = 0.3125) differed significantly between call frequency treatments. These results are striking because they suggest that O. pumilio males respond aggressively to a wide range of call characteristics. We also found that male brightness did not affect responses (Call length: F = 0.8484, DF = 3, P = 0.4781.  Response Time: F = 1.0574, DF = 3, P = 0.3813). Future work should identify the full range of chirp frequencies that can invoke a response in this species. We also note that we found some evidence for mimicry of call frequency by responders; this could be a topic for future work.

Oophaga pumilio

Playing manipulated calls to poison dart frogs

Ethan, Emma, and McKenna at work

Monkey business: Environmental impacts on monkey grouping behavior in a lowland tropical rainforest

Jessica Brown, Katie Hoffman, Zach Mader

La Selva Biological Station is one of the most important ecological research locations in the New World tropics. It is in a protected area of lowland rainforest, providing researchers with rare access to vulnerable populations of plants and animals. However, the station itself is large and could itself have an effect on species in the park. To test this hypothesis, we studied distribution patterns of La Selva’s three species of monkeys: howler monkeys (large, slow-moving vegetarians), white-faced capuchins (small, insectivorous monkeys), and spider monkeys (large, mobile opportunists). Monkeys are an important part of pristine rainforest ecosystems and are heavily influenced by habitat loss and other human disturbances. We focused on how the presence of the research station affects the distribution and relative positioning within groups, an indicator of group stress.  Humans may be seen as a predator to monkeys, thus we predicted that individuals within groups would cluster together when groups were closer to the station. We tested this prediction by recording species, group size, number of trees occupied, and the spread of individuals during surveys over the course of two days. We used two different ways to estimate dispersal between the monkeys: the number of trees occupied by the group and the spread of individuals (= the distance between the most separated monkeys within a group). We found that capuchins are more likely to occupy more trees (F₁,₁₂=4.479, p= 0.0378) and have a larger spread (F₁,₁₂=10.973, p=0.0024) than spider monkeys (howler monkeys had intermediate spread/individual). Our main result was that, after controlling for group size, groups further from the stations had a larger spread among individuals (F₁,₁₂=13.338, p=0.003) and a trend toward occupying more trees simultaneously (F₁,₁₂=3.712, p=0.078). These results suggest that the La Selva station affects monkey behavior. Future studies should investigate whether changes result from repeated contact with humans or changes in habitat structure associated with the station and its grounds.

Howler monkeys photographed by the researchers

A white-faced capuchin

Jess, Zach, and Katie collecting data

If you’re feeling froggy: Amphibian predation risk differences between forest types at La Selva Biological Station

Brennen Arendt, Nick Hable, Madison Gonsior, Jenny Walz

Amphibian populations are declining across the globe. As a result, there is a pressing need for studies on the factors that influence amphibian population stability. A recent study at La Selva Biological Station in Costa Rica showed that amphibian populations have changed significantly over the last 35 years (Whitfield et al. 2007) declining in old-growth forests but increasing in secondary forest. Abandoned cacao plantations, a type of secondary forests, are previously disturbed areas that contain remaining cacao trees. These trees undergo yearly flushes, dropping their leaves and adding to leaf litter. Whitfield et al. (2007) speculated that relative increases in amphibians in secondary forest (abandoned cacao plantations) may be due to higher leaf litter density that in turn increases in available amphibian habitat. If leaf litter habitat is greater in secondary forest, it follows that predation risk will also be significantly higher in such habitat. The prediction emerges from the ideal free distribution model, which states that predators will arrange themselves proportionally to prey abundance. Here we first confirmed habitat differences between old-growth and secondary forest predicted by Whitfield et al. (2007). We found that there was 1.5 times more leaf litter (t=7.155, DF=10.04, P < 0.001) and 2.4 times higher soil moisture (t=2.389, DF=6.249, P = 0.026) in secondary forests than in old-growth forests. Light intensity did not differ significantly between forest types (t=0.1725, DF=11.971, P = 0.567). Second, we tested for differences in predation risk between habitats using clay model frogs. We created and placed 56 clay frogs in each habitat, then analyzed attack frequency between each forest type to estimate predation risk. Habitat type did not have a significant effect on predation risk (x²=2.176, p=0.1402), although the general trend of predation risk supported our hypothesis with 16.1% attack rate in abandoned cacao plantation compared to a 7.14% attack rate in old-growth forest. Although populations of amphibians are increasing in secondary forests, our results suggest that this growth may be dampened by predation, limiting the total potential of growth in these habitats. This could mean that the amphibian population growth in secondary habitats may not be able to offset the declines of amphibian populations in old-growth forests.

Clay frogs ready for deployment

Nick and Jenny checking for attacks on clay frog models

Fish ‘n Chip(s): How fish community diversity affects prey capture in a tropical stream

Sara Osborne, Zachary George, Quinn Whiting

Although biodiversity loss is pressing global concern, research is still needed in many systems to identify how species diversity affects ecosystem function. Within aquatic environments, fish can affect several ecosystem properties including nutrient cycling. However, the impact of fish on aspects of nutrient cycling such as prey capture can depend on fish diversity and community composition. Understanding the role of fish community composition is particularly relevant given that human impacts, such as dams, can favor opportunistic species over equilibrium species in fish assemblages. Here, we studied how different microhabitats and fish community features affect prey capture rates in a tropical stream. We predicted that greater prey capture rate would be associated with several habitat variables (high canopy coverage, shallow waters, slower flow rate, and smaller pool area). In addition, we predicted that both higher overall fish abundance and lower fish diversity would increase prey capture rate because such communities would have more fish and relatively more opportunistic feeders such as Astyanax aeneus. We studied nine microhabitats within the Sabalo River within La Selva Biological Station, a protected lowland rainforest site in Costa Rica. At each location, we seine netted in triplicate to analyze fish abundance and species diversity. We then measured area, canopy coverage, flow rate, and depth of the microhabitats.  To determine prey capture rate, we dropped flecks of tuna and timed how long it took for them to be attacked by fish. A stepwise multiple regression analysis showed that abiotic factors explained 68% of the variation in capture efficiency, and the best-fit model showed that capture efficiency was associated with increased depth (p=0.041), more canopy coverage (p=0.078), and faster flow rate (p=0.092). Explanations for these include that deeper waters have more Astyanax aeneus, higher canopy coverage results in more insects falling into the stream (so fish are more accustomed to capture falling food), and faster flow rate increases the need to capture food quickly before it moves downstream. Surprisingly, capture efficiency was not associated with overall fish abundance, but was strongly correlated with lower species diversity (p=0.0005, R²=0.8433, n=9). Less diverse communities may be dominated by insectivorous fish, leading to an increase in capture efficiency. Our results suggest that changing certain stream dynamics due to deforestation and damming will have negative effects on nutrient cycling influenced by fish. Deforestation results in less canopy coverage over streams, resulting is less prey for the insectivores, and damming reduces flow rate which eliminates microhabitats that favor fish with higher capture efficiency, forcing these fish into the same microhabitat as lower capture efficiency fish and out competing them for food sources.

Astyanax aeneus (be careful with the pronunciation Sara)

Quinn and Zach seine netting

Sitting on the patio eating breakfast at La Selva Biological Station, in a lowland tropical rainforest on the Caribbean slope of Costa Rica, we are surrounded by colorful tanagers, hummingbirds, and manakins. We hear the calls of parrots, laughing falcons, and howler monkeys. Walking across the narrow bridge suspended across the Rio Puerto Viejo, we see iguanas sunning on top of giant Ficus trees, toucans tussling for fruit among the branches, and schools of fruit-eating fish in the water below. We hear loud squawks and look up to see a pair of scarlet macaws flying in the distance. This is a magical place, and it is easy to imagine that we are deep within a pristine jungle.

And yet, human impacts are all around. La Selva is surrounded on three sides by agricultural land.  Banana, pineapple, and palm plantations have carved up the landscape in recent decades. We can hear trucks on the nearby road, and some days the drone of crop-dusters is incessant as they apply pesticides to fields. Agriculture and ecotourism are the two pillars of the economy here in the Caribbean lowlands, one dedicated to the production of food and the other to the preservation of nature.

Google map image of the Caribbean slope of Costa Rica.  San Jose is visible in the top left.  The dark green is rain forest, mostly protected in national parks.  The light green is agricultural land, mostly large-scale banana and pineapple plantations run by multi-national companies.

On Saturday we visited a different type of farm—Finca Sura—a small-scale operation with a diverse array of crops. Don Rodolpho led us around his 9-acre estate, teaching us about different fruit trees, and the important roles that insects, hummingbirds, and bats play in pollinating his fruit. We picked pineapples, which Don Rodolpho effortlessly diced with several machete chops. He explained how no pesticides or nutrients are used on his farm, which results in smaller fruits that could not be exported, but, we all agreed that this was the best pineapple we’ve have ever eaten. He told us how many people who are allergic to pineapple are able to eat his fruits with no problems, indicating that it is often the chemical residue that people are sensitive to. He explained that frogs breed in the tiny pools of water in the tops of his pineapples, something that would never happen in a chemical-intensive operation. He showed us his pond full of tilapia, where visitors can catch their lunch. When I asked him whether birds eat his fish, he replied that of course herons and kingfishers hunt in his pond, but there is plenty to go around.

We’ve been thinking about Don Rodolpho’s farm as a model of sustainable agro-tourism, where food can be produced in a way that benefits nature and supports the local economy. Below are student reflections on this innovative concept and on the charismatic man behind it.

It was another normal early morning down here in Costa Rica. Filled with wonder and uncertainty about what is to come from the day. A normal day has been filled with hiking and research. Today we took a break from the hiking and drove a couple miles outside of La Selva (a huge biological station where we are staying) to Sura Farm. This is a family owned farm and we were greeted by the owner, Rudy. He was one of the most lively and passionate people I have met. He began to show us around his farm, and with each new turn, there was a new type of crop that they were growing. From pineapples, to rubber trees, to yucca, to cacao, to peppers and even some tomato-looking fruit that tasted like a warhead (those extremely sour hard candies that my mother hates). After touring much of the farms and even having the chance to plant our own pineapples we sat down in their recently renovated dining area. We were served fresh juice from multiple different fruits and some bread made from pineapples. I was told we were “going to a pineapple farm” with no knowledge of what to expect. I was surprised at each new plant and with the continual excitement by our new friend Rudy. So what did I learn/gain from this outing? I learned about the viability of true organic farming. I learned that sugar cane and ginger smashed together into a juice tastes delicious. I learned how to cut down and drink a coconut with ease. But most importantly, I learned that even in the most remote of places that people like Rudy do exist and are full of knowledge I could not have learned in a classroom. I’m learning in the most authentic way possible- straight from the source.

-Evan Kiel

Upon arrival at Finca Sura, we had no idea what to expect. We stepped out of the bus onto the trail as we were greeted by Rudy, our personal tour guide who just happened to be a local that only spoke Spanish. This presented a language barrier, but this barrier was quickly brought down by Emma, our own group member and personal translator. As the tour began Rudy showed us all the flora and fauna that his organic pineapple plantation had to offer, and we were all in awe of his knowledge. Rudy also let us do many activities such as planting pineapples, but he also took the time to interact with us on a personal level. His personality was one that brought smiles to our faces, and his hospitality is something that will not be soon forgotten.

-Nick Hable

The Sura estate is an all organic farm that grows a wide variety of produce such as ginger, sugarcane, bananas and its main crop being the pineapple. This small farm uses tourism to help raise awareness about eco-friendly farming practices and is a perfect example of the push towards sustainable agriculture here in Costa Rica. Our small UST group was given the privilege to tour the grounds and go behind the scenes of what it takes to grow all natural vegetation and the tasteful rewards as a result of the non-chemical practices. Upon our arrival we were given a warm welcome by the owner, Rodolpho, who was also our tour guide. He began the tour by giving us a brief history of the grounds and the common vegetation seen. One example is the pink banana palm which is a useful plant to help attract wildlife to its sweet fruits and distract them from the temptation of eating the valuable crops held deeper in the midst of the estate. Rodolpho would explain the types of vegetation grown, the methods used to grow them and what popular foods and uses each crop possesses. One such crop includes the farm’s main harvest, pineapple. To help prevent the spread of any potential diseases or large losses of crop yields due to wildlife infestation, Rodolpho separates his crops into different patches all around his fields. His plots have a maximum growing limit of 3 years and a break of harvest for 1 year per plot, allowing the soil to recuperate to be grown on again for another 3 years; and so on and so forth. Our group not only got to taste the sweet flavor of the freshly cut pineapple but we also had the opportunity to help Rodolpho plant more pineapple sprouts.  Signs throughout the farm show future visitors which groups planted each row of pineapples and participated in his sustainable farming practices. The tour comprised of eating fresh ginger, coconut milk and coconut meat, cinnamon bark, interacting with his livestock and ending with a tasteful snack of pineapple bread and handmade sugarcane and ginger juice. This event was not only academically enjoyable but was also a unique experience to participate in environmentally friendly methods to care for the land while gaining tasteful rewards and making new friends in the process.

-Emma Squires-Sperling

Visiting the Sura Farm was such a unique and rewarding experience. Growing up on a farm myself, it was very interesting to compare and contrasts the differences and similarities between a conventional farm in the Midwest and an organic farm in the tropics. As many people know, monoculture is becoming more and more popular in the U.S.; on my farm at home we only raise corn and soybeans. On the contrary, the organic Sura Farm had more tropical fruits and spices than I could count on one hand: pineapple, coconut, tomatoes, cacao, sugar cane, yucca, pepper, and ginger filled hectare after hectare of farmland. Not only did we get to see the different fields and trees with this produce, but we got to try it all (that is right after we watched them hand-pick it fresh of the plant). Not only did we get to try these amazing tropical foods, we also got to help them continue on their sustainable practices by planting the crown of the pineapple that we had just eaten. Taking what we had just eaten and putting it back into the ground for it to grow a new fruit was very different from my experience of agriculture, where the seeds planted are delivered to our farm in large, fifty pound bags. Being able to see first-hand how other cultures produce food was an experience that has broadened both my understanding and appreciation of the many agricultural practices that allow me to eat the large variety of fruits and vegetables I consume on a daily basis.

-Sara Osborne

Our January-term course, BIOL 211: Introduction to Field Ecology, focuses on independent projects. Our students are sophomores, juniors, and seniors. Only a few have taken an advanced ecology course. Students did everything for their projects – they came up with the idea, developed the design, executed it, and presented their results. They had ~5 days to work on projects from start to finish.

Our first site, Rara Avis Nature Reserve, is a mid-elevation site on the Atlantic slope of the Cordillero Central in Costa Rica. The site receives ~8.3m of rain each year. The 357-hectare reserve is mostly secondary forest, but it borders a large national park (Braulio Carillo).

Here are the students’ abstracts:

A Tad too Close for Comfort

Jessica Brown, Madison Gonsior, Sara Osborne, Quinn Whiting

Tadpoles face predation from many organisms, including birds, crabs, frogs, and other tadpoles. As a result, tadpoles may often sacrifice foraging opportunities to stay safe. However, specific strategies used to avoid predation may differ among habitats with different predation risks, inducing different tradeoff priorities. In this study, we compared predation avoidance behaviors among tadpoles at Rara Avis, a mid-elevation tropical rainforest.  We tested behaviors in tadpoles from two habitats, the Attelobus river (hereafter = “river tadpoles”) and smaller streams in the forest (“pond tadpoles”). River tadpoles inhabit exposed pools with rocky substrate; pond tadpoles inhabit pools under closed canopy with muddy substrate that is easily disturbed. We used a series of experiments to test whether river vs. pond tadpoles differed in (1) hiding behavior in a controlled, undisturbed environment, (2) hiding behavior in a controlled, disturbed environment, (3) reaction distance (how close a simulated predator can get to a tadpole before the tadpole flees) in natural habitats, and (4) escape responses in natural habitats. We found that, in a controlled environments, river tadpoles hid under rocks more often than pond tadpoles in both undisturbed (t=3.879, DF=9.471, p=0.003) and disturbed (X²=16.576, DF=1, p<0.001) conditions. In natural environments, reaction distance for river tadpoles was 3 times less for river tadpoles than for pond tadpoles (t=3.272, DF=17.99, p=0.002), but river tadpoles traveled farther than did pond tadpoles once they were disturbed by simulated predator attack (F₁=6.278, p=0.017). In contrast, pond tadpoles in the natural environment were more likely than river tadpoles to hide (X²=15.268, DF=1, p<0.001). We speculate that sediment, which only exists in pond habitats, is a key driver of these behavioral differences. Sediment could signal predation risk for pond tadpoles that would allow for greater reaction distance. Sediment could also provide hiding locations for pond tadpoles (but not river tadpoles), reducing their need for longer escape distances. Regardless of the mechanism, our results suggest that environments select for different anti-predator strategies in this system.

The Attelobus river

Sara measuring reaction distance

Quinn, Madison, and Jess at work

Bat sh*t crazy

McKenna Reid, Jenny Walz, Ethan Ridgewell

Animals often damage plants to create nest sites. Although this damage suggests that this type of interaction is parasitic (i.e., one party benefits at the expense of the other), it is possible that animals provide other benefits to plants such that the relationship is mutualistic (i.e., both parties benefit). One way that nest animals could benefit plants is by providing excreting waste products that provide concentrated nutrients for plants to use. Here, we studied an ideal system for exploring a possible mutualism between a nest-making animal Uroderma bilobatum (the Common Tent Bat) and its host plant (a common palm, Geonoma sp.). U. bilobatum form tents by making incisions in the leaves of Geonoma palms. We compared palm height, number of leaves, distance from water, the extent to which the plant is surrounded by other vegetation (protected), and chlorophyll levels between palms with bat tents and palms without bat tents. We found that leaves with bat tents had similar chlorophyll levels as leaves on the same plant without bat tents (t=0.284, df=7, p=0.784); this result suggests that bat tents have little effect on plant photosynthetic capacity. A few results suggest that bat presence is associated with higher quality Geonoma palms. First, leaf chlorophyll in undamaged leaves on bat-associated plants had almost significantly higher leaf chlorophyll levels than did plants without bat tents (t=1.929, df=12.1, p=0.078). Second, a multiple logistic regression model including plant height, number of leaves, distance from water, and protection showed that bats were associated with significantly taller plants (X² = 7.796, df = 1, p = 0.005). We also found a significant interaction between plant height and number of leaves (X² = 5.084, df = 1, p = 0.024) – bats were only associated with shorter plants if those plants had an exceptionally large number of leaves. There are two interpretations for these results. First, the “bats as parasites” explanation suggests that bats select higher quality plants to provide them with better protection. Alternatively, the “bats as mutualists” interpretation suggests that bat presence increases the quality of plants. The presence of significant amounts of nutrient-rich bat guano under bat tents suggest that the “bats as mutualists” explanation warrants further study.

Jenny, Ethan, and McKenna

a bat tent from above

a common tent bat tent from below

Studying Mammalian Pack Behavior in Coatis

Brennan Arendt, Evan Keil, Emma Squires-Sperling

Within mammalian packs, individuals of different ages often have distinct role. For example, in whale pods, the eldest female plays the role of the matriarch; teaching younger individuals how to survive. Coatis, a member of the raccoon family, are found throughout Costa Rica and travel in packs. Although packs consist of individuals differing in age and size, there is still much to learn about how these factors affect behavior of animals living in pristine environments. We studied age-related behavioral differences in coatis in Rara Avis Nature Preserve, a secluded mid-elevation location bordering Braulio Carrillo National Park in central Costa Rica. Our test group was a pack of coatis that regularly fed at a compost site close to the dining center at Rara Avis. We predicted that older (larger) individuals would be more vigilant compared to younger coatis because they provided parental care. Younger coatis were predicted to be more adventurous than adult coatis because they were less sensitive to predation risk. Furthermore, we predicted older individuals would feed less, walk more and be more alert compared to younger coatis and that tail positions would not differ between age groups. These hypotheses were tested by baiting and observing the coatis at the compost site and then taking pictures of individuals at 1-min intervals. We found that adults showed more vigilance (proportion time spent with head raised) than younger coatis; the difference in vigilance was nearly statistically significant (df = 22, p = 0.051). In contrast, tail positioning did not differ significantly between age groups (p = 0.634). Although preliminary, our results suggest that coatis in remote locations show division of labor within packs based on individual age.

Brennan, Emma, and Evan at the Coati Research Center

A young coati

The ecological niche of an endemic species

Zach George, Nick Hable, Katie Hoffman, Zach Mader

Endemism, when species are only present in a specific geographic location, is relatively common for species in biodiversity hotspots like the rainforests of Costa Rica. Understanding the specific traits of endemic species is particularly important for conservation, especially given climate changes occurring in many areas. In this study, we studied the niche breadth (range of conditions in which a species is found) of the stained-glass palms (Geonoma epetiolata), a species endemic to mid-elevation rainforest habitat near Rara Avis Nature Reserve in central Costa Rica. We compared plant abundance, soil moisture, and canopy cover above plants for both stained-glass palms and fishtail palms (Geonoma spp.), a close relative to Geonoma epetiolata. We predicted that stained-glass palms would be more abundant than fish tail palms because they were specifically adapted to this location. We also predicted that stained-glass palms would occur in narrower soil moisture and canopy openness ranges than fish tail palms because of their specific requirements associated with endemism. We found that fish tail palms were substantially more abundant than stained-glass palms, indicating that the endemic species did not have a competitive advantage in this system. We also that fish tail palms had a 45% wider range of soil moisture levels and were more likely to be found across a range of canopy covers than stained-glass palms. Our results suggest that stained-glass palms are extremely vulnerable to local extirpation because of their limited abundance and narrow niche. Given that the population at Rara Avis is one of the few remaining populations in Costa Rica, our results suggest this species should receive additional conservation attention.

Zach M, Katie, Zach G, and Nick with a stained glass palm

Zach estimating canopy cover

During our first full day in Costa Rica (January 6), we asked the students in our BIOL 211: Intro to Field Ecology course to write a cultural essay. Specifically, we wanted them to visit a site in San Jose (the capital city) and then write about how Costa Rican culture has affected the natural world, or how the natural world is reflected in a particular aspect of the culture. We had a number of excellent submissions, but we chose two winners (by Evan Keil and McKenna Reid). Here they are:

My cultural extravaganza in San Jose

Evan Keil

Evan Keil with his new friend Paquito

Walking through San Jose opened my eyes to a different world. I’ve been across the globe, yet every time that I am immersed in a new culture I am completely humbled by their way of living. Highlights of the trip include meeting a man (Martin) who carries around his rooster named Paquito, feeding the pigeons, walking through countless markets and shops and finally dancing with a local band who was playing their music in the streets. We are always told how we need to schedule less and how we need to stay off of our countless screens… yet do we? The Costa Rican people move slower, they have real conversations and have shown me a way of life that seems to be worth living. It is becoming more and more apparent how needed the environment is to facilitate this way of living, and how it shaped it.

The markets that we walked through were filled with fresh fruits and vegetables, tons of fish and any type of meat you can imagine, the areas that weren’t filled with food were filled with cultural items and home-made trinkets (as my mother would say). It was obvious that without the surrounding fields and farms that none of this would be possible. After talking to the locals we heard of a fruit market that only runs from midnight to the early morning. I am picturing a family farm filled with apples and bananas and countless other fruits that have been harvested, all filled into the back of a truck. I see this truck making a couple hour drive into the city to and setting up their mini stand in the middle of the street. This truck is joined by other families and the street begins to fill up. I then picture another family who does their daily shopping at this market. I see the mother taking her child through the market in search for the best deals and best fruit in town. These two families meet and, after agreeing on a price, they have what they wanted and have benefited one another. Again, without the surrounding environment, none of this is possible. The availability of rain and sunshine has shaped the areas outside of the city into abundant farmland.

The peaceful demeanor of the people I see being shaped by the rural areas. Obviously deep into the city there will always be the stereotypical on-edge taxi driver who will honk at anything and pedestrians that will eternally assume they have the right-of-way and continue to cause accidents. However, when we took the time to stop and attempt a conversation with a local at their stand we began to see who they really are. The men that were playing their music in the street are a prime example of this. We stopped to listen, but shortly after they realized we were foreign to their city they invited us in to dance. Of course we were hesitant, but after being encouraged by the entire band Sara (Osborne) joined in. She had (still has) no dancing skills, but the light in all of the band members’ eyes when she attempted to dance was something I will never forget.

During our drive and monstrous hike to (our first research site) Rara Avis, I began to see why these people have become so peaceful while enveloped by this country. It seems like there isn’t really any way around it. Since we have left the city, it has been raining for probably 80% of the time. As I am writing this, we are sitting around a table in one of the few dry areas on this mountain. Some people are napping, some are writing and the others are talking. There isn’t an urgency to be busy, there isn’t a drive to go find something to do, and honestly there aren’t really the means to do so. Life is simple. There is no snapchat or Facebook, no twitter and Instagram and no electricity for the most part. The forest has formed this culture, and the most obvious way is by limiting the use of technology. The two workers sitting behind me, named Margarita and Doris, are having a conversation while sipping on some water. The more I observe, the more obvious is it that people not only enjoy this more simple life, but thrive in it. The rural families that grew up in their farms and within the jungle are the ones that shaped and continue to shape Costa Rica as it is today. Again, this call back to nature and simpler times is all facilitated by the surrounding thick of the jungle and the several inches of rain that we have seen over the past few hours.

This whole concept of a simpler life being shaped by the environment is something that I, among other I would assume, am completely oblivious to. When I look outside my window at school, I see more houses, surrounded by more houses and more roads. There aren’t any means to be exposed to these sorts of things growing up in suburbia Minnesota. We have our lakes and our boats and take the occasional trip to Mexico (staying in a 5 star resort, of course), yet we don’t know the quality and way of life outside of our little white picket fenced in yards. There can and has been a case for the interconnectedness of our country and how far we have come. But being thrown into a culture so polar opposite of our own, I am beginning to see the necessity for a change. And as much as my idealistic and egotistic head would like to believe, I will not be able to change the world and the likelihood of America changing its ways are essentially zero. This formation of a culture so simple and yet so seemingly connected came from its environment and came from the infinite rain that accompanies it. I hope to continue learning and tapping further into this way of life, after all, it is only day 3.

The Culture of Costa Rica

McKenna Reid

Mercado Central in San Jose

Costa Rica has an incredibly unique environment and culture. There are creatures in the beautiful forests of this country that cannot be found anywhere else in this world. Just like the organisms that live here, the Costa Rican’s also have a unique and inspiring culture. From the short time I have spent here I feel as if I have been able to observe and learn a lot about the mutual relationship between the locals and the surrounding environment, specifically when it comes to the locals making a living for themselves and their families. In many aspects of their culture, we are able to see a reflection between the natural environment and the traditions that they practice.

I thought that a good location to go within the city was the central market (Mercado Central). From the outside it looks like any of the other surrounding buildings, but once you find yourself inside its walls, it’s as if you entered another part of the world. The market building itself is made up of nearly one hundred smaller stands, all packed together in an uncomfortable and overcrowded space. The walkways are no more than four feet wide and the ceilings are close to 20 feet high. Each stand was crammed with as many goods as they could fit, many of them over pouring into the already too small walkway. There were stands packed with just about anything you could need or imagine: dead sea creatures, little toys and trinkets, arrangements of nuts, different spices, jewelry, bunnies and chicks, vegetables, beef. At one stand I walked by the workers were selling knives and at the shop directly next to it the employees were selling children’s toys. I was amazed by the amount of goods that were available in this one market center. The most common things to find were small food stands. Some of these stands were only selling the raw materials needed for cooking, such as peppers and meat, but the majority of them were selling meals that were cooked right in front of you. The smells were incredible, so I decided to stay and observe how the meals were prepared. There was one stand whose food stood out to me in particular, and that was because the cooks had finished tacos and burritos placed on large leaves. I was curious as to why they were doing this, but I didn’t have the time to ask because of how busy the chefs were. Jonathon, our Costa Rican guide here at Rara Avis, helped to enlighten me as to why the women had these tacos and burritos on leaves. While we were hiking today, Jonathon handed another student a giant leaf and asked him to try and crinkle it up as much as he could. After working at it for about 10 seconds, Jonathon grabbed it and smoothed it out. The leaf had little to no tears or wrinkles left in it, even after the attempted mangling. Jonathon went on to explain that these leaves are commonly used for cooking because of how tough and strong they are. When cooking a burrito, the chef only needs to place the ingredients in the leaf, roll it up, and let it sit in boiling water to cook. The leaves are so strong that they will not tear or get worn from the extreme heat of the boiling water.

Mercado Central in San Jose

I’ve been on this trip for 4 days now, and I have learned more about dependence than I really ever have before. By seeing the chefs use the giant leaves to cook food, it really put into perspective that we need and use the environment for everything. The locals at the market center rely on their meats, fruits and vegetables in order to survive and make a living in this world. They use leaves found in the forest because they’re stronger and better than any man made object the user could find. I think the most important thing that I noticed, not only in the market center but all of San Jose, is how integrated nature is in their everyday lives. Costa Rican food production seems to be the greatest export the country has, and because of this, it is one of the most common things being sold on the streets. A classmate pointed out to me that there aren’t any “organic restaurants” to be seen because almost everything here is organic. I talked to a few locals about what their thoughts on pesticides were and none of them understood why we would willingly (and knowingly) put those chemicals into our bodies. They were shocked that so little of the foods in the United States are not organic. I think that because the Costa Rican culture relies so heavily on the beauty of its land and its foods, that they really have a deep respect for the nature surrounding them. The respect that they have is necessary for the survival of the surrounding forests and oceans. If the locals lacked the respect they have, they would likely tear the forests down branch by branch in order to make more money for themselves. It’s amazing to see how important each party’s respect is for the other’s survival.

It was a truly incredible experience that I was able to submerge myself in the Costa Rican culture and observe the ways in which they provide for themselves and their families. The market central showed me how important the environment is for so many people, and why it is that they have so much respect for the nature that surrounds them. Because San Jose is the largest city here, I’m sure that the true dependence and importance of the natural world for the Costa Rican’s was not fully shown. I am so excited to continue learning about these types of interactions and seeing how we need the natural environment just as much as it needs us for its survival.

The lodge at Rara Avis

Rara Avis, 357 hectare private reserve connected to Braulio Carrillo National Park, was one of Costa Rica’s first ecotourism lodges. It was established in 1983 to demonstrate that ecotourism could help conserve tropical rainforests by generating more revenue for local residents than other land uses (such as logging and cattle ranching).

Rara Avis has been a model for ecotourism in Costa Rica. It started a butterfly chrysalis production project that served as a model for family operations throughout the area. It had one of the first “canopy access devices” that allowed researchers and visitors to see all of the activity that occurs high up in the trees. In the 1990s, Rara Avis was featured in many publications including the New York Times Magazine and the Chicago Tribune. It is also a biodiversity hotspot: it has over 500 tree species, over 350 species of birds, and high diversity of amphibians and reptiles, and many endemic species including the stained-glass window palm (Geonoma epetiolata).

Everything grows on everything at Rara Avis

One of the reasons we picked Rara Avis for our first destination for our course (BIOL 211: Introduction to Field Ecology) is because of its remoteness and simplicity. When Rara Avis was first established, it took ~6 hours by road to get from San Jose to Las Horquetas, the town nearest to Rara Avis. From Las Horquetas, you had to travel 15km by horse or on foot, and the last 6 km was too rough for horses. Now, travel from San Jose to Las Horquetas is fairly easy – our class traveled by bus in a little over an hour – though access from Las Horquetas is still pretty tough. We traveled by tractor over extremely rough road for ~5km, and then we walked (mostly uphill, through dense rainforest) for several hours to make it the rest of the way. At lower elevations, the road went through pastures lined with barbed-wire fence. Further along, we walked mostly through intact forest. One stop along the way was in a clearing called El Plastico, a former prison colony deep in the forest. Our guides told us that prisoners were brought to the site blindfolded and had to hunt for their own food. Now, the site is managed by a conservation-minded, non-profit organization called Selvatica. The most striking aspect of the El Plastico building was the abundance of golden orb spiders (Nephila clavipes), which had webs that covered much of the area under the rafters. It’s an interesting experience to be surrounded by spiders that are the size of your palm.

The feeling of remoteness at Rara Avis is enhanced by the rain. The site receives over 27 feet (8.2 m) a year. Luckily for us, January is the beginning of the “dry” season (although even in January, the monthly average rainfall is 26 inches (~67cm)). Everywhere you look, you can see the effects of all that rainfall. The forest is filled with moss and ferns. Most trees are completely covered in bromeliads, philodendrons, and other epiphytes (plants that grow on trees). The forest is dense and dark, trails are slippery, and all of the wooden planks and steps are in varying states of rot.

The simplicity of Rara Avis is also evident everywhere. We have electricity in only a couple of buildings, and only for about 5 hours a day. Most of the buildings are open air (no windows and doors). The suspension bridge to cross the river at the edge of the station is pretty rickety and can only support 3 people at a time. Our free time is spent playing cards, going on night hikes, or swimming below the double waterfall.

Chip Small in our classroom

We were interested in what the students thought about spending a week in this place, so we asked them for some reflections at the end of our stay. Here they are:

McKenna Reid: “Jenny Walz and I had been hiking all over Rara Avis trying to find Geonoma plants with bats in them, and it’s so amazing to me that we already knew exactly what we’re looking for. We were searching one of the trails for our plants when we came across a beautiful stream that cut right through the forest. We decided to take in the beautiful morning sun by laying out on some rocks that were peeking out of the flowing water. As we were laying there, drifting off into our own thoughts, I kept trying to wrap my head around the fact that I was in the middle of nowhere, in a rainforest, in one of the most beautiful places I have ever seen. My “real life” was thousands of miles away, but all I cared about in that moment was the beauty that surrounded me. It was one of those eye-opening experiences that you have when you realize just how small you are in this world, and that you will never be able to see or fully understand all of earth’s tiny, beautiful secrets. Lounging in that river, realizing my appreciation for the world around me, is one of those moments that will be with me for the rest of my life.“

Madison Gonsior: “When we first began the journey from San Jose to Rara Avis, I thought it entailed just a 1.5 hour bus ride and a 1.5 hour tractor ride. There was only one part from that statement that was missing: a 3 hour hike through the pouring rain in the middle of the jungle. Six hours of travel was beyond worth the amazing scenery, projects and memories we got to make during our time spent at Rara Avis. Rara Avis is truly a hidden gem that allowed for us to come closer together as a group and mentally grow as individuals. Time spent at the waterfall, on the trails and seeing poisonous snakes, howler monkeys and coatis are just some of the few memories we were able to share during our short stay, but life-changing and memory making stay at Rara Avis.”

Ethan Ridgewell: “My first impression of Rara Avis is close to the exact opposite of my final impression. When we first arrived and I looked upon the buildings, I thought that this place was a falling apart. There were spider webs everywhere, we had no running water and everything just seemed old. It turns out the spider webs were not cleaned up because the staff at Rara Avis did not want to disturb the wild life. By day two, one of the staff members had fixed the water situation and we now had running water. While everything does still seem old, there is a lot of history and serenity in this place. There have been three times in my life that I have been at a loss of words. The first time I saw this waterfall was the one of those time. I have visited that waterfall every day to enjoy the beauty and, of course, to go swimming.  In any one of the buildings, there is the constant sound of the nearby waterfall reminding me of the beauty and tempting me to drop everything I am doing and just go for a swim. My final impression is one of beauty, peace, serenity and relaxation. If I could, I would visit Rara Avis every year, just to get away from everything and relax.”

Zach George: “Rara Avis is an isolated oasis in the mountain rainforests of Costa Rica. Very few people travel to this part of the country, and the resulting isolation is refreshing. Taking a week away from the hustle and bustle of population and getting away from social media and technology allows one to take a step back and reflect on the environment in a way which would not be possible elsewhere. Seeing one’s own footprint as the only mark of human interaction with the jungle, days after you last went down a trail and a stunning waterfall to swim in makes you feel as if the rainforest is your own personal playground and classroom to focus on the environment.”

A sample of monsters covered: Godzilla, dragons, chimeras, werewolves, vampires, zombies, aliens, the Wendigo

You’ve seen them in movies and TV shows. You’ve woken up in a cold sweat after dreaming about them. Maybe you’ve avoided them as much as possible. Monsters are a pervasive part of our modern culture, and they have been for most of recorded human history. You may love them, hate them, or fear them, but can monsters tell us anything about actual biology? I posed this question to students in Biology of Monsters (BIOL 398) at the end of this semester after we spent 15 weeks delving into what makes monsters tick, or not, and here are some excerpts of what they had to say:

By observing monster characteristics and trying to determine how and why they can or can’t exist, you actually learn about real biology. In order to disprove, you must first understand. Monsters serve as an exciting and engaging model to teach organismal, developmental, and evolutionary biology. Disproving or trying to prove existence also promotes creativity and helps us see biological connections that may have gone unnoticed and unexplored.

We are able to learn many comparative aspects of anatomy, physiology, psychology, genetics, developmental biology, evolutionary biology, and immunology. By understanding how these mechanisms work in hypothetical models, we can understand our own biology and the world around us.

By looking at what cannot exist, you are able to view the limitations on real biology and the ways that actual biology is constrained.

By studying monsters we can learn a lot about real biology, such as physical constraints in form and function of an organism in order to understand how that organism is alive. It helps us understand trade-offs and developmental issues for organisms, and how to apply that information to real-life organisms.

Actually, a lot of biological ideas can be applied to monsters. By looking at realistic properties of monsters we can study real biology. But also, by studying what is unrealistic about monsters, we can understand the real biology that constrains extant organisms.

You can absolutely learn so much by studying monsters. This class has challenged me both intellectually and creatively to come up with reasons why monsters can’t exist. You have to think about concepts such as psychology, scaling limitations, organ functions, transmission, niche specialization, and so many more. The class is an awesome way to learn how to apply biological concepts in a creative and extremely interesting and engaging way.

By learning about the limits of “real biology” and why these monsters can’t exist it gives us a better understanding of the world around us. This class encompasses many of the building blocks of developing life, and learning about them is important to understand existing life.

Monsters are basically creatures that already possess biological characteristics that are based off real-life animals, only their biology is enhanced, and so by looking at the constraints as to why monsters don’t exist we can see the limits of biology.

Don’t worry, this zombie couldn’t exist. If you want to know the many, many reasons why, just ask someone who took this course…

This semester, my upper-division Animal Behavior class (BIOL 330) conducted a study on the feeding behavior of house cats. We recruited our friends and families to volunteer their cats as research subjects. Students in the class came up with a research plan and carried out all aspects of the project. Pairs of students wrote short blog posts about the results. I’ve posted a great one below by seniors Shane McWirther and Nick Loken. There were several other great ones, and we had contributions from every class member (listed below). Thanks so much to all of the participants that took the time to complete the study. Check out the results – they’re great!

To Eat or Not To Eat Protein? That Is The Question 

http://scriptorsenex.blogspot.com/2013/02/shakespeare-on-saturday.htm

It’s that time again – Snickers is sitting at his empty bowl with a look of despair. You completely forgot to run to the store and get him his usual bag of Fancy Feast. Finals are coming up and you have a term paper due tomorrow. As much as you don’t want to waste time driving through traffic to get more food, nobody likes an agitated cat. You rev up your 96’ Honda and speed down to PetSmart. This trip has been made many times before; walk through the doors, take a right and awkwardly power walk down to aisle 8 where the Frisky Feast awaits you. You go to grab the bag but it’s nowhere to be found. What now? The term paper looms over you and you grab the first bag of cat food you see. He won’t even know the difference. It’s just cat food. But what if he could?

Researchers have discovered that food preferences for many animals are not simply determined by chance. Balancing macronutrients through selective foraging has been found throughout the animal kingdom. Primates (Felton et. al 2009) and mice (Sorensen et. al 2008) are known to maintain stable protein levels in their diet over time regardless of caloric intake. These observations are potentially explained by the Protein Leverage Hypothesis, which posits that animals adjust their level of food intake to reach a constant protein intake level.

The aim of the current study is to see whether cats adhere to the Protein Level Hypothesis and choose foods based on their macronutrient content. Specifically, we tested 3 predictions: (1) If cats selectively forage to maintain stable protein levels, those pre-treated with low protein foods will compensate by eating protein rich foods when given a choice between foods with varying protein content; (2) If cats do not selectively forage, they will prefer whatever food they are pretreated with regardless of its macronutrient composition; (3) If a cats current nutritional state does not affect its foraging habits, pre-treatment will have no effect on foraging habits of cats when given access to foods with varying macronutrient content. The results of the study could provide support for the Protein Leverage Hypothesis and in turn inform pet owners on eating habits of their beloved felines and help them make better choices when scouring the grocery aisles for the perfect cat food.

Methods:

Table 1. Major components of Purina One Urinary Tract (UT) and Healthy Metabolism (HM) dry foods

Thirty-eight cats (from 25 cat owners) were recruited to participate in the study. Cat owners received a package containing one bag of low carbohydrate + fat, high-protein cat food (Purina Healthy Metabolism (HM)), one bag of high carbohydrate + fat, low-protein cat food (Purina Urinary Tract Health (UT)), one bag containing a mixture of both formulas, and one pre-treatment bag containing solely UT or HM formula (complete dietary information is listed in Table 1). All food bags were labeled and weighed prior to distribution. Cats were weaned onto bags containing a mixture of the two formulas for four days by serving it along with their customary food brand. On day five, cats were given access to only the pre-treatment bag containing solely HM or UT formula. On day six, cats were given equal access to both HM and UT formulas. Bags from days five and six were returned to the researchers and weighed upon arrival in the lab. Multiple cat homes were treated as one participant. Data was analyzed using JMP.

Results & Discussion: 

Figure 1. Relationship between pre-feeding treatment and % protein eaten when cats free fed one day later

We found that cats consumed the same amount of pre-treatment food on day five of the experiment regardless of what formula the bag contained (Average intake of UT = 120.4g, HM = 126.4g, p>0.05). This result shows that cats ate whatever was given to them in the absence food choice. However, cats were observed to eat almost twice as much of the high protein HM formula compared to the low protein UT formula when given equal access to each on day six (Average intake of HM = 82.0g, UT = 43.1g, p<0.05). This result indicates that cats were selectively foraging for protein. However, we also found that pre-feeding conditions significantly affected foraging behavior on a subsequent day. Specifically, we found that cats pre-treated with the low-protein UT formula ate a significantly higher proportion of protein (higher HM:UT consumption) on day six compared to cats pre-treated with HM formula (Figure 1, p<0.05).

Our study is the first to test for nutrient balancing in domestic cats using a citizen-science study design. The protein compensation that we found on day six observed in UT pre-treated cats provides strong support for our main prediction – that cats selectively forage to maintain nutrient balance. Prediction two was supported by the fact that UT pre-treated cats did not consume a larger ratio of UT:HM formula which would be indicated by consumption of a lower proportion of protein on day six (Figure 1). These results are consistent with a recent study using lab cats (Hewson-Hughes et al. 2011). Although the exact feeding methods of the cat owners were not directly observed, we do not believe that this impacted our results since owners were given detailed instructions on the protocol.

Many cat owners do not take into account the macronutrient composition of the cat food they are buying even though it may be in their cat’s best interests. Being force-fed low-protein foods may cause many cats to over-eat in order for them to stabilize protein intake in their diet. Over-eating can lead to several different health disorders, possibly shortening the lifespan of cats. So next time you’re rushing through the store looking to buy a new bag of cat food, take the time to stop and look at its nutritional composition. This simple choice could be the difference between a fat cat and a happy cat.

Citations:

Felton AM, Felton A, Raubenheimer D, Simpson SJ, Foley WJ, Wood JT, Lindenmayer DB (2009) Protein content of diets dictates the daily energy intake of a free-ranging primate. Behavioral Ecology 20: 685-690.

Hewson-Hughes AK, Hewson-Hughes VL, Miller AT, Hall SR, Simpson SJ, Raubenheimer D (2011). Geometric analysis of macronutrient selection in the adult domestic cat, Felis catus. Journal of Experimental Biology 214: 1039-1051.

Sørensen A Mayntz D, Raubenheimer D, Simpson SJ (2008) Protein-leverage in mice: The geometry of macronutrient balancing and consequences for fat deposition. Obesity 16: 566-571.

About the authors: Shane McWhirter & Nick Loken our senior Neuroscience majors at the University of St. Thomas. Other class contributors were Sam Bach, Maureen Carberry, James Giorgi, Justin Hummelgard, Cory Jensen, Angela Kramlinger, Lauren Kvam, Abby Lown, Mike McGoldrick, Lauren Mumm, Losha Ndemeno-Tegomoh, Jillian Nielsen, Zac Novaczyk, Meghan O’Reilly, Luis Ortega, Danny Oseid, Marchellie Sheldon, Tori Shepard, Kale Siebert, Ariel Steele, Lexi Tartar, Asha Urban, and Carissa Van Slooten.

Social behavior is a very complex phenomenon, as we all know. Although we understand a great deal about why many aspects of social behavior evolve, we know surprisingly little about what mechanisms evolve to cause species differences in social behavior. One interesting, and somewhat surprising, aspect of behavioral evolution is that similar types of social behavior can evolve in distantly related species. This convergent evolution is due to the distantly related species experiencing similar environmental/social pressures. For example, maternal care strategies in placental and marsupial mammals have converged, as has web making in Hawaiian spiders and echolocation call structure in bats. My colleague and I studied a potential mechanism to explain behavioral convergence in Caribbean Anolis lizards.

Caribbean anoles display convergent evolution in habitat use, morphology, and behavior. The picture above shows the different “types” of lizards you can find on Jamaica, Hispaniola, Cuba, Puerto Rico, and the Bahamas.

Caribbean anoles are best known for convergent evolution in habitat use and the anatomy associated with locomotion in different parts of trees in the forests in which they live. That is, on different Greater Antillean islands, the same lizard shapes have re-evolved independently based on where they live in the forest. But wait, it gets better! They also display striking convergence in their levels of aggression. Twig anoles are laid-back lizards that rarely display, whereas trunk-ground anoles display at anything that moves! Other species fall somewhere in between. The astute reader may be thinking that differences in aggression may be due to differences in that “male hormone” testosterone, and that’s what we tested. Based on decades of literature that led us to our hypotheses, we tested whether convergent evolution in aggression is due to convergent evolution in testosterone levels, and the results were surprising. Lizard species with high aggression had low testosterone levels (and vice versa) on three of four islands that we studied. Puerto Rican species showed the relationship that we expected: high testosterone = high aggression.

Two extremes from the Bahamas: Anolis angusticeps (left), a twig anole that lives life slowly, and Anolis sagrei (right), a trunk-ground anole that wants you to believe that he can take you out.

Our results suggest that the same social behavior can result from the evolution of different mechanisms. This is a phenomenon that functional morphologists call “many-to-one mapping.” The idea is that the same functional end can be reached by multiple mechanistic means. It seems that being an aggressive anole (or not!) can evolve by changes in different mechanistic pathways. For some testosterone levels have changed in a predictable manner, but in others it is likely due to changes in hormone receptors or some other hormone system completely. We’re currently looking into these possibilities, so stay tuned. For more info, check out our webpage!

Three trunk-ground anoles. Each species evolved the same general body shape (and aggressive behavior) independently from different ancestors.

Las Cruces Biological Station was the second stop for the J-term Biology course in Costa Rica. Las Cruces is a mid-elevation site that receives about 4m of rain a year. The station is connected to a small (~300 hectare) primary forest fragment. It also has the Wilson Botanical Garden – the most famous botanical garden in Central America – filled with rare and endangered plants from the New and Old World tropics. We had about a week at Las Cruces. We asked our students to come up with a project idea and then execute the research during that time. It’s impressive that they were able to do high quality work during such a short period of time. Here are their abstracts (along with some pictures and videos):

Does release from herbivory facilitate plant invasions? A test in a tropical rainforest

Jorgen Kvaal, Ryan Merry, Morgan Reeve

Invasive species are major threats to biodiversity in many ecosystems, including tropical rainforests.  One mechanism that could allow exotic species to invade new ecosystems is if these species face less predation and parasitism in novel areas than in their native habitats.  At Las Cruces Biological Research Station in San Vito Costa Rica, three non-native plant species have escaped from the station’s Wilson Botanical Garden into the native forest and are visibly encroaching on native species.  Here, we tested whether parasitism reduction may allow these non-native species to outcompete native inhabitants.  Specifically, we hypothesized that herbivory and epiphyte loads (=parasitism) would be reduced on non-native than on similar native species, and this reduction in parasitism would lead to higher growth rates.  We paired each of three non-native species with a native species that was present where the non-native species was found, was being pushed to the periphery of the available habitat, and had a growth form similar to that of the paired non-native species. We assessed plants for herbivory and epiphyte cover, and assayed photosynthetic levels and leaf nitrate content (a rough indicator of leaf quality).  We found that parasitism was ~9x greater (main effect of native/invasive status: F_1,24 = 12.96, P=0.001), photosynthetic levels were significantly lower (F_1,17=20.941, p=0.0003) and nitrate content was significantly lower (F=6.778, p=0.0005) for native plants than for non-native plants. These results suggest that reductions in parasitism result in greater allocation of resources to growth in non-native plants which could in turn allow for a competitive advantage versus native counterparts.

La Selva Biological Station, Costa Rica: On Wednesday, January 22 at ~4:30 pm, Morgan Reeve, Meg Thompson, and Jake Anderson saw evidence of a puma (Puma concolor). They were on the CCC trail ~300m from the La Selva station clearing. Initially, they saw foot-long scat filled with peccary hair, teeth, and armadillo skin. The scat was directly on the walking path. After discovering the scat, they walked down the path ~100 meters and then heard two low growls, consistent with sounds of a puma (supported by on-line research). All three then heard something large run off into the forest. One person (Jake) clearly saw the back end of a large beige animal 60-75cm tall. Jake said it ran off “like a puma” (supported by on-line video research). La Selva, which is connected to the Braulio Carrillo National Park on the Caribbean slope of Costa Rica, supports 5 of the 6 feline species in Costa Rica. Naturalist Kenneth Alfaro said that there are about one direct puma sighting a year at La Selva. Probably the best support for feline conservation is participating in low-impact ecotourism that values pristine forest protection (e.g., visit La Selva).

The scat was about 30cm long before it was cut in pieces for analysis

detailed view of the scat

Meg, Jake, and Morgan

This January, our class – Introduction to Field Ecology (BIOL 211) – is conducting research at sites across Costa Rica. Our first research site was on the Osa Peninsula near Corcovado National Park (we have a post about our accommodations here). At the site, the students were responsible for coming up with a project idea, developing an experimental design, executing the project, and creating a presentation. They had to do all of that in just over two days. Many of these students have little experience with ecology, and none of them had ever been to the tropics. Here are abstracts and pictures from their incredible work:

Communication behavior in the endangered scarlet macaw

Jorgen Kvaal, Erik Sathe, and Taylor Schuweiler

Communication among conspecifics can improve foraging and anti-predator success. Many birds communicate with conspecifics through vocalization while living in groups of two or more. However, the function of conspecific communication likely depends on behavioral context. In this study, we studied vocalization patterns of scarlet macaws (Ara macao) near Corcovado National Park on the Osa Peninsula of Costa Rica. Scarlet macaws are endangered, but the Osa may support the largest macaw population (800-1200 individuals) in Central America. Here, we compared macaw vocalization patterns in flight vs. while perched; we also tested whether vocalization frequency varied with group size. We predicted that call frequency would be higher for individuals flying than for those perched because of the greater need for activity coordination in flight. Similarly, we predicted that individual call frequency would increase with group size because of the increased need for coordination in larger groups. We found that, as predicted, call frequency was significantly higher while an individual was flying than while perched. We also found that per capita call frequency was dependent on group size while flying but not while perched. Interestingly, we also found a significant difference in mean call frequency between the most vocal and least vocal individuals within a group, particularly while birds were perching. These patterns suggest that call-response behaviors are critical for organizing flight patterns, which likely help in navigation and anti-predator success.

Team Macaw: Jorgen, Taylor, and Erik

A pair of scarlet macaws

gold miners panning near Luna

Honestly, we didn’t plan it this way. Our course, Introduction to Field Ecology, was scheduled to stay at the Sirena field station deep inside Corcovado National Park on the Osa Peninsula in Costa Rica. To get to that station, we would have had to have walked 6-8 hours through the rain forest (from Los Patos to Sirena). We then would have camped for 4 nights on a platform in the forest. It’s a fairly primitive site: supplies are all brought in by boat or small plane, there are only a few hours of generator-produced power each day, and even mosquito nets don’t provide enough protection from the biting insects. In short, it’s an intense off-the-grid experience deep in a pristine rainforest (see our post about our 2012 adventure here).

by Kate Hanson with help from Biol 211 coursemates

Our course – BIOL 211: Introduction to Field Ecology – is visiting 4 sites in Costa Rica this January. Our group’s first venture into the Costa Rican forest was at the Cuericí Biological Station in Cerro de la Muerte. We left the urban center of San Jose unsure of what to expect. We could see the changing landscape and feel a chill in the air as the bus climbed higher into the mountains. After hours of driving, our driver Jorge pulled over and explained that he couldn’t take us any further. In fact, he had no idea how we were supposed to get to the station from there. The terrain was much too steep and dangerous for the bus to maneuver (after all, Cerro de la Muerte means mountain of death.) We waited for the station’s owner, Carlos Solana, to come find us. I was expecting Carlos to be an able-bodied man with some four-wheel drive trucks to whisk us away. Much to my surprise, the Carlos that arrived was just a gentle older man with kind eyes. And he had just one, small truck. It became clear that the plan was to hike the 5 km to the station. As we descended the slopes of the mountain of death, it began to pour. After trudging over the gravel hills in the rain, Carlos’ rustic log cabin was more than a welcome site.

the Cuerici station at Cerro de la Muerte

Carlos Solano (2014)

near the Cuerici station

Every even-year January, the University of St. Thomas sponsors an Introduction to Field Ecology course in Costa Rica. The main component of the course involves student-led ecological research projects at various field sites across Costa Rica. Before getting started, the course spends a day in San Jose working on a vicious stats assignment and exploring the city. We asked students to write short essays to describe their experiences and reflect on how San Jose culture relates to the natural world. We chose two entries (by Jorgen Kvaal and Morgan Reeve) to present here. All pictures are by Meg Thompson.

The Happiest Place on Earth?

by Jorgen Kvaal

The first thing that I noticed as I stepped off the plane in Costa Rica was a large banner that read “Welcome to the happiest place on Earth”. The poster was accentuated with beautiful tropical animals and plants that I look forward to seeing while I’m here.

in a park in San Jose

I started doubting the validity of that slogan, however, after spending my first night in the capital city of San Jose. During a night out, some of my classmates and I were frequently harassed by local riff raff asking for money; they probably thought we were a group of naïve foreigners ripe for the taking. In truth, that is exactly what we were; straight off the plane in a foreign country that none of us had ever been to before. Nevertheless, I believe we were undeserving of some of the horribly vulgar comments shouted in our direction, specifically towards my female counterparts. I went to bed that night thinking that even my hometown of St. Paul MN seemed happier that the town of San Jose.

This poem was written and performed by UST seniors Daniel Volovets (on guitar) and Joshua Serre (reciter) as an extra credit assignment for Dr. Sarah Heimovics’ class BIOL/NSCI 398: Topics in Behavioral Neuroendocrinology.  In this poem, a prairie vole laments the fact that he must engage in copulatory behavior in order to form a pair bond, as he adheres to a conservative moral ideology and wishes to save such activities for marriage.  Josh and Daniel highlight much of the research covered in class about the neuroendocrine basis of social affiliation, referencing several of the major findings of Aragona et al. (2006) “Nucleus accumbens dopamine differentially mediates the formation of maintenance of monogamous pair bonds.” Nature Neuroscience. Vol. 9 Number 1 (133-39).

Several exciting developments to report in our aquaponics research.

Recent UST graduate Isaac Bergstrom presenting aquaponics research at the Ecological Society of America meeting in Minneapolis.

First, Isaac Bergstrom presented a poster at the Ecological Society of America meeting on the research we did this spring on nutrient efficiency in coupled vermicompost-aquaponics systems (where we attempt to answer the question: “How can we turn coffee grounds into tilapia and basil).

In the Bible Jesus turned water into wine, but can students at the University of St. Thomas turn coffee grounds into tilapia and basil?  Turning food waste into new food is a question being explored by the students in my Urban Ecosystem Ecology course.

Because cities have a lot of people living in a relatively small area, large inputs of food, energy, water, and other materials are required in order to support these urban ecosystems.  Our waste products leave the system in the form of garbage going to the landfill, nutrients in wastewater and runoff entering the river, and carbon dioxide emitted to the atmosphere.  Cities exemplify open systems, with lots of inputs, lots of outputs, and lots of waste.

Below is a summary of a study conducted by Dr. Adam Kay‘s Animal Behavior class (BIOL 330) at the University of St. Thomas in April 2013. Students collected data with help from friends and families. Students then wrote blog posts that they submitted as an assignment. Below are excerpts (in quotations) from these posts, with some text (from Adam) to tie things together. A complete list of authors (i.e., students in the class) is at the end of the post. We are grateful to the owners and dogs that participated in the study. 

“Imagine a scenario in which you and your sibling are paid to walk your family’s dog. That sounds great at first. But then imagine you find out that your sibling is being paid twice as much as you to do the same task. Not fair! How would you respond to such a situation? You might put less effort into doing the chore or maybe even refuse to cooperate altogether because you know you’re not being fairly compensated. This behavior, a resistance to perceived unfairness in social situations, is known as inequity aversion, and its existence is thought to explain some uncooperative behaviors in otherwise cooperative species.”

There’s more than one way to skin a cat, as the saying goes. Although this euphemism is a tired cliché, it applies to how morphological traits may evolve. To solve a functional ‘problem’, species may evolve different morphological means to reach the same functional end. This is called “many-to-one mapping” in evolutionary biology. My colleagues and I studied how a fascinating group of insects, stalk-eyed flies, might morphologically overcome impaired flight brought about by their ridiculously exaggerated eye stalks, the span of which can be longer than the fly’s body itself!

One of the more dimorphic species, showing the extreme differences between males and females in eye span. Yes, the eyes are on the tips of those stalks!

Calling all biology-oriented students thinking about where to go to university – here is a post for you!

The Biology Department at the University of St. Thomas is a national leader for undergraduate-led research. We invest a lot in our teaching, but we also are committed to our research with the aim of making an impact on our field (see our recent publications here). Unlike at many larger schools, undergraduate students in our department play leading roles in our research programs. In fact, many of our students present their research at national meetings and co-author papers with their faculty mentors. We strive to create an exceptional environment for students interested in learning how to be the research leaders of tomorrow.

Kurt Illig

Adolescence can be an awkward time. For humans, the teenage years can be marked by behaviors that are not seen in people of other ages. These behaviors can be relatively benign, such as dressing in all black and going to all-night dance parties, and they can be more dangerous and risky, such as indiscriminate sexual behavior and drug use. Teens usually outgrow most of these behaviors (how many “emo” adults do you see?), but drug use is particularly problematic; research has shown that someone who first uses drugs as an adolescent is far more likely to become chronically addicted than someone who first uses as an adult. Why?

Ecology Gangham style? Well, not quite. But this June UST Biology’s Hangkyo Lim and Tony Lewno will be leading a course that will travel around Korea to learn about the culture and ecology of this biologically diverse area. The course will provide upper-division Biology elective credit. Tuition will be similar to on-campus credit costs. There are only a few slots still available, so contact Hangkyo (lim94497@stthomas.edu) or Tony (awlewno@stthomas.edu) right away if you’re interested. The course is also open to students from other ACTC schools. A full description of the course is below.

BIOL 398: Topics in Ecology and Culture of Korea

Hangkyo at Haeinsa Temple

This course is designed  to help students learn about the biology and culture across the diverse environmental conditions of Korea.  The ecological variety and cultural heritage found on the Korean peninsula are ideally suited to serve the course objectives: 1) the peninsula exhibits a wide range of diverse Northeastern Asian ecosystems, which are not well represented in ecological studies, 2) the Korean peninsula has been populated for longer than 25,000 years and has a well-preserved historical and cultural heritage, and 3) the country is one of the fastest developing countries in Northeast Asia, which provides ample opportunities for studying human impacts on and interactions with ecological systems. Many Korean instructors and their students will support and participate in the program both logistically and intellectually thanks to the connections of the program director.

Phosphorus and the evolution of sexual reproduction 

Mating Potamopyrgus antipodarum snails (photo Bart Zijlstra)

Why do animals reproduce sexually? The answer may seem obvious until you consider that some animal species actually reproduce by making identical clones without input from a partner. Cloning, also referred to as asexual reproduction, has advantages. Most importantly, it results in parents transferring their full complement of genetic information to their offspring; in contrast, sexual parents only transfer half of their genes (the other half comes from the other parent). This advantage is enormous, making it paradoxical that sex is so common in the animal kingdom.

A sign on a building in downtown Christchurch

At first glance, Christchurch looks like a war zone. We’ve spent several days here this January (for our project on the ecology of sexual reproduction in a freshwater snail), and we’ve seen shocking evidence of the major earthquakes of 2010 and 2011. There are ruined buildings, piles of rubble, and empty lots throughout the downtown. It’s so different from the quaint city Adam remembers from 2007 when he was here for a conference with UST student Katie Theisen and her sister Becky. However, as we’ve walked around we’ve found so many imaginative recovery projects being developed around the damage. What’s particularly interesting to us about these projects is that they share many features with ecological sustainability efforts happening elsewhere.

Katie and Becky Theisen in downtown Christchurch in 2007

City Center was quaint in 2007

The Christchurch Cathedral, 2007

During our field sampling in New Zealand this January, we’ve found that it’s easy to get excited about all of the beautiful landscapes and striking plants and animals. However, the more we learn about New Zealand ecology, the more we realize that we have to have a nuanced emotional response to what we see. New Zealand has many invasive species, many of which do substantial damage to native ecosystems. It turns out that much of the biology that catches our attention only exists in New Zealand because of recent introductions resulting from human activities.

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Field ecologists need to be adaptable, patient, and persistent. We often work in remote locations under variable conditions with limited resources. These limitations certainly make things more difficult, but it’s also really fun to figure out ways to get around the constraints and unexpected challenges that come our way.

Whitebait can solve most problems. It’s a fried pancake filled with fish fry (those white worm-like things)

This January, UST Biology major Liz Chambers and I (along with our colleagues Maurine Neiman from the University of Iowa and Amy Krist from the University of Wyoming) are measuring ecological characteristics of various lakes on the south island of New Zealand. Our funding for the project comes from a grant from the National Geographic Society (to Maurine). Our main goal is to test our hypothesis about the relationship between environmental phosphorus limitation and the relative success of sexual and asexual forms of the freshwater snail, Potamopyrgus antipodarum (for more information about the project, see here). Toward this end, we’re sampling 15 lakes across the south island to estimate the extent of nutrient limitation for algae (the main food for our snails) and to determine algae chemical composition. We’re also collecting snails for various biochemical analyses that will help us estimate the extent to which their growth is limited by phosphorus availability.

Why have sex? It’s a difficult question to ask without sounding creepy. But the answer isn’t as obvious as you might think.

A male trying to offset the two-fold cost of sex

Evolutionary biologists have shown that sexually reproducing organisms should theoretically be at a disadvantage when competing with asexual organisms. The reason for this is that sexual females need male partners to reproduce, whereas asexuals can reproduce by themselves (“who needs guys anyway?” says Liz). Therefore, all else being equal, sexual females (which produce both males and females) will produce only half as many descendants over the long term as asexuals will. The production of males is referred to as the “two-fold cost of sexual reproduction”, and it should result in sexual forms being outcompeted by asexual forms. However, sexual reproduction is very common, especially in animals. Why sex remains so common despite this two-fold cost has been termed the “queen of questions” in evolutionary biology.

Below are posts from UST Biology’s Kerri Carlson and one of her students, Ryan Augustin. They are reflections on a departmental seminar from this semester given by David Largaespada from the University of Minnesota Cancer Center.

Dr. Carslon’s reflections

It has always amazed me how scientists are able to harness the power of naturally occurring phenomenon to develop novel tools to enhance our understanding of genetics.   The use of plasmids and restriction enzymes revolutionized the way we study genes through the advent of gene cloning.  An understanding of homologous recombination led to gene knock out technologies in mice.  In Dr. Largespada’s seminar we were presented with another example: the use of a transposon system called Sleeping Beauty to identify novel cancer genes.  (Transposons are DNA elements that are capable of “jumping” from one DNA location to another DNA location in the cell of an organism-and in some cases cause mutations).

Students in Dr. Jill Manske‘s class (BIOL 467- Emerging Infectious Diseases) completed a semester-long project on dual use research (life sciences research that yields information with the potential to be misused to threaten public health or national security) and the case of influenza A virus subtype H5N1. As part of  the project, the class wrote an informal opinion piece. Here it is!

Pandemic in the Periphery:

How Dangerous the Search for a Cure Could Be

Edward Aika, Daisy Alfaro, Erica Bye, Terese Heighway, Abby House, Ashton Johnson, Brandilyn Reak, Toni Teague, Linda Thomas, Paul Zerfas

21 December, 2012

Department of Biology, University of St. Thomas

Introduction to Influenza: The Common Misconception of the Common “Flu”

Dr. Dalma Martinovic-Weigelt and friends sampling from the Bahai farm in Minneapolis

The Biology Department at the University of St. Thomas is committed to integrating research, teaching, and community outreach activities. On Friday December 14 (2012), our new sophomore-level class (Biology 209 – Biology of Sustainability) had a symposium to display student projects from a service-learning lab on sustainable agriculture. The lab was designed to assess soil quality and gardening practices for our community partner, the Youth Farm and Market Project. Youth Farms is a Twin Cities organization that provides experiential education and training activities for over 600 youths organized around the themes of urban agriculture and local food production. Our UST students collected samples from 13 urban farms in the Youth Farms program and analyzed soil samples for nutrients, heavy metals, and other measures of soil quality. Students then analyzed and summarized the results, and prepared products to disseminate their findings. They were allowed to choose among three target audiences: farm managers, youths involved in the program, or the UST community. Student groups produced a variety of products including prezis, web sites, brochures, handouts, and posters. There was even a children’s book and a board game! We awarded prizes for best offerings in each of the categories.  It was a hard choice because there were so many good ones. Here are the winners:

UST Biology’s Chip Small and colleagues recently published a study in Limnology & Oceanography, a leading ecosystem science journal. Below is a general audience description. The full article is available here.

Chip Small on Lake Superior

Gazing out across Lake Superior from a rocky beach on Minnesota’s north shore, it’s easy to imagine that this massive lake has been unaffected by humans.  The crystal-clear waters of this lake, which holds 10% of Earth’s liquid freshwater, hide the fact that, over the past century, nitrate levels have increased more than five-fold.  Scientists have assumed that this increase is simply due to external inputs such as nitrogen deposition from the atmosphere.  However, a new study published in the journal Limnology & Oceanography, my colleagues and I show that a group of microbes that was only recently discovered is playing an essential role in maintaining an imbalanced nitrogen cycle.

UST Biology’s Jadin Jackson and colleagues recently published a study in the Journal of Neuroscience. Below is a general audience description. The full article is available here.

Learning to associate rewarding experiences with the location at which they occurred is a fundamental adaptation for survival, that allows us to return to a food source or other primary reward in order to get more of something valuable. Using rats, we studied the simultaneous activity in two important brain regions involved in learning these reward-place associations and planning actions that will lead to reward: the hippocampus, involved in place and episode learning; and the ventral striatum which uses location and reward-related information for the planning of actions. We found that neurons in the hippocampus most reliably represented the location of an animal when the animal was able to predict that a reward would be available, and that ventral striatal neurons included more spatial information in their activity during this same period. Additionally, the activity of neurons in the hippocampus much more precisely locked to the time it would take the animal to reach a reward, fitting with the involvement of the hippocampus in human episodic memory. This study clarifies the information being processed by these two important brain regions and how the presence of reward-predictive cues in an environment will bias that information.

Lansink C.,  Jackson J.C., Lankelma  J., Ito R. , Robbins T.W. , Everitt B., Pennartz C.M.A. (2012)  Reward cues in space: commonalities and differences in neural coding by hippocampal and ventral striatal ensembles. Journal of Neuroscience 32:12444-12459

Can where an organism lives on the planet influence something as seemingly unrelated as how much steroid hormone they have circulating in their bodies? It turns out, yes, it can! The reason for this is that in the tropics there is a longer amount of time to potentially breed, and further away from the Tropics (toward the poles) the time available to breed (the breeding season) gets shorter and shorter. During the breeding season, males of many vertebrate species compete intensely over access to females that are ready to reproduce. The steroid hormone testosterone has an important role in ramping up males for reproduction and is typically elevated during the breeding season. Corticosterone, another steroid hormone, typically associated with “stress” and the response to stress, is also moderately elevated during this period, probably to facilitate the uptake, storage, and mobilization of energy needed for breeding. In places where the breeding season is short, for example at high latitudes, competition over females may be more intense than at places where breeding is extended, such as in the Tropics. In a recent study, my colleagues and I sought to test whether species having a shorter breeding season, and presumably more intense competition for mates during this short window of time, would have higher steroid hormones levels compared to species living in areas closer to the Tropics where there is a larger window of time for breeding. To do this, we examined variation in circulating levels of testosterone and corticosterone, as well as latitude and length of the breeding season in two major vertebrate classes: amphibians and reptiles.

Jon Foley, from the Institute on the Environment, recently gave a seminar  entitled “Can we feed a growing world and sustain the planet?” in the UST Biology Department seminar. (If you missed it, you can watch Dr. Foley’s TEDxTC talk at http://www.youtube.com/watch?v=uJhgGbRA6Hk). Below are comments on the seminar by Dr. Chip Small and Breanna Arndt from our department.

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Student projects in Costa Rica – part 2: From poison dart frogs to cannibalistic tadpoles at La Selva Biological Station

The January-term course in Costa Rica, Introduction to Field Ecology course, is over. I’m sure everyone is happy to be home, but I hope the memories of the course will stay with people for a long time. I’m finally getting my life in order again, and I thought I would share some information about our final stop on the course – La Selva Biological Station – and post abstracts from the amazing projects that folks did there.

lunch time for our group at La Selva

an eyelash viper, picture from Tyler Abrahamson

La Selva was a great place for our course to visit. La Selva itself is fairly small (about 1600 hectares) but it is connected to the massive 36,000-hectare Braulio Carrillo National Park. The large combined area and the elevational gradient from lowlands to the 3500 meter peaks in Braulio Carrillo make this area a unique conservation area on the Caribbean slope. The flora and fauna are very diverse: there are over 700 species are trees at La Selva, a lot of beautiful snakes such as the eyelash viper (that many of us saw) and the dangerous and aggressive fer-de-lance (that one of us stepped on!), thousands of arthropod species such as the army ant Eciton burchelli (video), charismatic amphibians like the strawberry poison dart frog (see below), and more than 400 species of birds (representing almost half of Costa Rica’s bird species) (here’s a gratuitous baby peccary video). There’s also extensive infrastructure at La Selva. There is also modern lab space, comfortable living quarters, a cafeteria, and an extensive trail system. Some of the trails through the forest are even paved. La Selva is really wet (it gets about 4 meters of rain a year) and a lot of foot traffic on paths would quickly degrade the surrounding area. Paved paths also make it easier for researchers to travel to their study sites; the station even rents bikes that you can ride along the paths (here’s a video from some of our group). The diversity and infrastructure is part of the reason that La Selva is one of the most important places for tropical research in the world: since the station was established by the Organization for Tropical Studies in 1968, there have been over 1600 scientific papers published based on research at the site.

{Editor’s note: This semester, UST senior Nick Michalak is doing an independent study in which he is reading and writing about prominent books in Biology that are written for a general audience (the “lay public”). Here is the first of his entries.]

Nick getting some inspiration

I’m mingling at a New Year’s party this past December, when the host calls me over to chime in on a discussion her fiancé and his friend are having. I bounce over, we exchange niceties, and the fiancé’s friend confidently states, “Psychology is a soft science.” He’s a chemical engineer, proud of his role as a “hard” scientist, and he goes on to say that, “You can ask a chemist to make a certain amount of a specific compound, and he can cook up almost exactly that amount. Psychology just doesn’t have that kind of predictive power.”

Maurine Neiman, formerly a post doc in our department and now an assistant professor in the Biology Department at the University of Iowa, recently had her research featured in a Huffington Post article about mating. You can check it out here: http://www.huffingtonpost.com/carin-bondar/no-eggs-no-problem_b_1250895.html

Beef and conservation in a tropical dry forest – notes from Palo Verde National Park

Entering the Palo Verde forest

A main reason that the Introduction to Field Ecology course comes to Costa Rica is so that we can use the rich biodiversity zones as natural laboratories for student-led research projects. Although there is a lot of biodiversity at individual sites, it is amazing how different the flora and fauna can be among the various sites. So far, we’ve traveled from a high elevation, oak-dominated forest at Cerro de la Muerte, to a lowland seasonally wet forest on the Pacific coast (Corcovado), to our recently departed dry forest location (Palo Verde). Visiting such different sites in a short period of time can make your head spin, but it has made for a great adventure.

marshlands at Palo Verde

Student-led ecology projects in a remote tropical forest

Lab courses in Biology provide students with training in many aspects of the scientific process, but students rarely have the opportunity to come up with and develop their own research questions. The Introduction to Field Ecology course,  which is organized almost exclusively around student-led projects, is an exception. The course travels to sites in Costa Rica for a month. Students spend a couple of days at each site making observations which they then use to generate a question about the ecology or behavior of organisms at the site. They then develop an experimental design, collect data to test predictions, and present their findings to the group. It is a great opportunity to employ their creativity, inquisitiveness, and effort to the process of discovery.

In the land of endangered species – sightings of the Baird’s tapir

Liz’s picture of a male tapir on the beach in Corcovado

Our Introduction to Field Ecology course spent last week at Corcovado National Park in SW Costa Rica. This park is the largest protected area of lowland forest on the Pacific coast of Central America. Larger parks can support populations of animals that have large home ranges, special habitat requirements, or are particularly at risk when in proximity to human settlements. Many of these species – jaguars, white-lipped peccaries, and scarlet macaws – are abundant in Corcovado, and they are one of the reasons why this place is such an exciting location to visit.

Braedon’s picture of a baby tapir in the Rio Claro

Probably our most exciting animal sighting at Corcovado was the Baird’s tapir, Tapirus bairdii. Baird’s tapir is the largest non-domesticated land mammal in Central America. It used to be abundant across its range from southern Mexico to northern Columbia. However, in 2002 it was listed as Endangered by the International Union for the Conservation of Nature (IUCN), which estimated that there were only about 5000 tapirs left in the wild. This number is down by at least a 50% in the last 30 years, and it’s expected to drop by at least another 50% in the next 30 years.

This January, UST senior Abbie Bruning is conducting research in Panama on how diet affects social immunity in the ant, Ectatomma ruidum. Since January 3rd, she has been on Barro Colorado Island in the Panama canal zone conducting research on her own. Below is a description of her experiences:

Abbie at work in the lab on BCI

A stint on Barro Colorado Island (Panama) in the dry season – by Abbie Bruning

                Coming back to Barro Colorado Island (BCI) has been a fun and exciting experience. I was previously on the island May through July of 2011. The atmosphere of the island is much different this time of year compared to the summer months. This is not only because the number of researchers are significantly reduced but also because, starting mid December, the dry season begins. During the dry season temperatures raise slightly and the humidity drops. The significant characteristic of the dry season is the large reduction of rain fall. During the rainy season there is a 40% to 50% chance of rain everyday which makes it very difficult to stay on schedule with field work. While during the dry season you’re lucky if you get a five minute cloud break from the sun, as my Irish skin can attest. (I am still trying to figure out how I got a sun burn while working under the rainforest canopy all day.) My first few days on BCI, my professor Adam and I collected ant colonies almost every day; it would have been impossible to have done that in the rainy season. (Here is a video of Abbie walking the stairs going into the forest. Here is Abbie going into the forest. She’s not wearing field clothes – this was a quick excursion to a canopy tower)

the “Ambient Soil Lab” on Barro Colorado Island

Reflections on culture and ecology in Costa Rica – by Leah Ruhland and Evan Nolander

Most of our course – Introduction to Field Ecology – in Costa Rica focuses on ecology research projects at various locations across the country. However, on our first day in the capital city, San Jose, we ask students to visit a cultural site and to write about how this aspect of Costa Rican culture has affected or is affected by the natural world. We had many great submissions, but we picked two exceptional posts for the blog. Here they are:

Walking to the “most biologically intense place on earth”

Corcovado National Park in southwestern Costa Rica is an amazing place to visit. It is one of the last large expanse of lowland tropical rainforest in Central America. Lowland rainforest is particularly important for conservation because much of the biodiversity in the tropics is located there. Unfortunately, lowland rainforest contains valuable tree species for logging, and it’s relatively easy to convert into agricultural land. Forest conversion not only destroys natural habitat, but the resulting habitat fragmentation makes it difficult to maintain viable populations of organisms with large ranges. Corcovado, with 263 square miles of continuous forest, is the largest primary tropical forest on the American Pacific coastline, and it is home to populations of some of the rarest animals in the New World tropics – Jaguars, Baird’s tapir, harpy eagles, scarlet macaws, white-lipped peccaries, and the Central American squirrel monkey.

Field Ecology in Costa Rica – A Visit to the Mountain of Death

This January, 14 UST students and 2 instructors are taking part in a field ecology course in Costa Rica. We’re going to visit a variety of forests and ecosystems, ranging from classic lowland tropical rain forest to the endangered tropical dry forests to misty, montane cloud forests. The focus of the course is teaching students how to conduct field-based ecological research. Costa Rica is a great environment for teaching field ecology because there is so much biological complexity. In this environment, students can come up with their own research questions and carry out simple observations or experiments to address them. It’s exciting for everyone when someone is able to discover something new about the biological world using simple tools, ingenuity, and the scientific method.

Student research in Panama – the beginning of an adventure

Today UST senior Abbie Bruning and I are traveling to Barro Colorado Island (BCI) in Panama to start a research project

Abbie with friend

on social immunity in ants. Abbie is going to be on BCI through January and will write several entries about her experiences. Today we wanted to write a quick entry describing a bit about our travels, with some information about Panama and the history of BCI thrown in.

Panama has been undergoing an economic boom over the last few years and signs of modernization are everywhere. The skyline of Panama City looks like Miami – glossy new skyscrapers pressed right up against the beach. But it’s really stressful in Panama City. It’s very noisy – drivers honk constantly (what are they honking for?) – and filled with smog. Crossing a street is treacherous – you just have to go for it. Luckily, there are some cool out-of-the way hostels that give some respite. A fun place to go is Luna’s Castle in the old part of the city (Casco Viejo), which still has a lot of old french colonial architecture – some it well-maintained, some of it crumbling.

I am not a fathead

I remember an episode one summer day when I was a teenager. I was daydreaming while I was riding my bike and I rode through a stop sign into an intersection. There was a car at the stop sign on the cross street and a tough-looking guy was watching me while leaning out his open window. He had started pulling out into the intersection and I almost hit him. As I clumsily tried to stop, the only thing he said was “fathead”. And then he drove off.

Perspective of an Undergraduate – Attending the ESA meeting in RENO 

(This is a guest post by Katie Miller, a senior Biology major)

Although intimidating as it might be for an undergraduate student to hop a plane to a new place they haven’t been before, possibly by themselves, and attend a big scientific meeting, I believe that it can be an extremely enriching experience. Recently, I temporarily vacated my undergraduate classes to attend the Entomological Society of America meeting in Reno, Nevada. For those who don’t know, this is the largest insect meeting in the world where scientists from almost every continent attend to present their research and attend professional networking and collaborative meetings. Upon the looming date of departure to the meeting, certain troubling thoughts occurred to me such as: “what if I don’t see anyone I know?”, “what if I mess up my presentation?”, and “what about my coursework!” Despite the potential hazards of attending a scientific meeting during the semester, there are numerous benefits that an undergraduate student can gain from attendance. During the meeting, I had a variety of different opportunities to learn about hot topics in Entomology and Ecology and about research related to my current project on ants.

 Introducing the Real Green Man

Humanity currently faces significant environmental challenges due to climate change, habitat destruction, overexploitation of natural resources, and biodiversity loss. These challenges are related to human population size, resource use, and waste production. Given that our population continues to grow and our per capita ecological footprint gets ever larger, there’s a lot of work for us to do. Is there any chance that we can make our society sustainable? Can we create a world in which we live happy lives in a vibrant society without degrading our natural systems? The short answer is YES: good descriptions of the policies that we need to enact can be found in recent books by Thomas Friedman and Paul Gilding. But we need passionate buy-in to create major societal restructuring needed to become sustainable. We need a war effort focused on reducing our environmental impact.

Population ecology and the coming of the zombie apocalypse

In 300 A.D there were 50-60 million humans, by 1804 there were 1 billion, and last week, the UN reported that there are now 7 billion of us. And more are coming. Given that the planet has a limited resource base, the human population cannot grow forever. Demographers describe constraints on population growth with a metaphor, the carrying capacity, which is the maximum population size that a habitat can support indefinitely. Population growth rate decreases to 0 as the population size approaches the carrying capacity. The processes that bring about this decrease in population growth rate are called negative density-dependent factors. These factors include the crappy aspects of civilization – food and shelter scarcity, violence among individuals, higher risk of disease, waste accumulation – as well as behaviors that reduce birth rates. As of now, resource use per person is still increasing as the global economy continues to grow (albeit unevenly). But it’s impossible for the human population to increase in size indefinitely – even if technology increases resource use efficiency. Population growth rates will decrease, and this decrease will be due to negative density-dependent factors. Hopefully, we’ll figure out a way to reduce birth rates and resource use rates without mayhem. I’m not optimistic.

Humanity’s future is bright, or maybe it’s not

The United Nations last week reported that the earth’s population has now reached 7 billion. The 7 billionth person doesn’t change our social or ecological conditions in any fundamental way, but the milestone provides an opportunity for reflection on broad trends. What is in store for this mass of humanity? Will more creative minds give us a better opportunity to develop technologies that enhance our quality of life? Or is the impact on the global ecosystem of so many humans moving us toward a catastrophic collapse?

Why I like Biology

(Note: I wrote the essay below for a popular science blog. It didn’t get published, but I can publish it here and I hope it’ll get the ball rolling with this blog)

I like biology because it has helped me understand who I am and how I fit into the world around me. As an undergraduate student, I struggled to understand why conflict and suffering seemed to be an inevitable aspect of the human experience. I searched for answers as a religious studies major at the University of North Carolina, but I never found anything deeply satisfying until I stumbled across E.O. Wilson’s “Sociobiology”, a wonderful book that describes social behavior from microbes to mammals. By the time I finished the famous final chapter, “Man: From sociobiology to sociology”, I was convinced that evolutionary biology had enormous potential to help explain human nature. Over time, I found that core evolutionary theory about social interactions – kin selection, parent-offspring conflict theory, sexual selection – provided explanations for my motivations that were far more satisfying than anything else I had been exposed to. Now, as a researcher and professor studying behavior, I have learned that ideas about the evolutionary underpinnings of human behavior are novel, interesting, and often challenging to students trying to figure out meaning and purpose in their world. Studies from the natural world describing complex behavior help students feel more connected to nature. One of my favorites is a study by Jeffrey Hoover and Scott Robinson that describes how cowbirds, which lay eggs in the nests of songbirds, use mafia-like behavior to ensure that the parasitized songbirds rear rather than destroy the cowbird eggs (Hoover and Robinson 2007). At the same time, studies of the adaptive significance of modern human behavior, for example the studies by Randy Thornhill, Steven Gangestad and others showing how odor attractiveness is sub-consciously associated with body symmetry (e.g., Thornhill and Gangestad 1999), or the study by Melissa Bateson and colleagues showing how the presence of a photograph of human eyes increases contributions to an honesty box (Bateson et al. 2006) often give students new insight into the motives underlying their social interactions. Given the complexities of modern life and the incredible challenges facing the global population, I hope that self-awareness gained through biology will help us understand causes and find remedies for our social ills.

Bateson M, Nettle D, Roberts G (2006) Cues of being watched enhance cooperation in a real-world setting. Biology Letters, 2, 412–414.

Hoover JP, Robinson SK (2007) Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs. Proceedings of the National Academy of Sciences of the United States of America, 104, 4479-4483.

Thornhill, R., & Gangestad, S. W. (1999). The scent of symmetry: A human pheromone that signals fitness? Evolution and Human Behavior, 20, 175-201.

Our New Blog!

The field of Biology has relevance for many of our major societal challenges and opportunities. Faculty in the Biology Department at the University of St. Thomas conduct research and teach classes that address societal issues, but we are also interested in generating a dialogue and sharing information with a broad community. The aim of this blog is to give department members an opportunity to share  information about their research, their teaching, their philosophy, or their opinions on recent biology-related news. We encourage comments on all posts. If guests (e.g., current students, department alums, other visitors) would like to post an entry, you can contact adam kay (adkay@stthomas.edu). Please include the phrase “Biophilia Blog entry” in the title of the email.