Monteverde Institute: Tropical Ecology and Conservation

Follow

• 

  Altitudinal distribution and niche partitioning of two Redstart species in Monteverde (Parulidae), May 2009

  Brad Nitta

  Global climate change is affecting habitat and species interactions globally (Sekerciouglu et al. 2008), including tropical montane regions (Pounds et al. 1999, Holmes 2000, Pounds et al. 2006). In Monteverde, Costa Rica, two species of warblers, the Collared Redstart (Myioborus torquatus) and the Slate-throated Redstart (M. miniatus), are known to partition altitudinally with a sizeable sympatric zone of overlap (Shopland 1985, Mahan 1998, Adams 2003). As with other species, global warming is thought to cause changes in the altitudinal distributions of both Redstarts. Both species are expected to move upward. To avoid competitive exclusion, niche partitioning should occur in the sympatric altitudinal zone. The purpose of this study is to establish the current altitudinal distribution of both species, and compare that to previous studies. Additionally, this study attempts to identify the presence and mechanism of niche partitioning between the species in their zone of overlap. Finally, it documents changes in relative species abundance of the two species over time. Altitude data, species data, and foraging height data for the two Redstart species were collected from primary and secondary forests in the Monteverde Cloud Forest Preserve, Santa Elena Cloud Forest Preserve, and trails on Cerro Amigos; all in Monteverde, Puntarenas, Costa Rica, and with altitudinal range from 1,400 to 1,750 m. Results from this study clearly indicate increased altitudinal changes. Slate- throated Redstarts, traditionally the lower altitude species, were observed up to 1,710 m in elevation; almost 200 m higher than previous studies done in the same forests report. The Collared Redstart was observed a minimum of 10 m higher than previous observations. More importantly, the Collared Redstart is now sympatric with the Slate- throated Redstart in the entire altitudinal distribution observed. Next, relative abundance of the Collared Redstart was found to be drastically lower than previous studies. The Collared Redstart made up less than 25% of the observations in this study, whereas it has consistently composed greater than 50% of observations in past studies. Finally, foraging height was found to be a significant mechanism of niche partitioning in the sympatric altitudinal zone. In this overlap zone, below 1,602 m Slate-throated Redstarts foraged at greater heights than Collared Redstarts, while above 1,602 m the opposite trend was observed. The findings of this study support the conclusion that global climate change has affected the distribution of species in Monteverde. Because the Slate-throated Redstart is now present at altitudes previously inhabited only by the Collared Redstart, a new equilibrium of relative species abundance will be reached through effective niche partitioning, or extinction will occur most likely resulting in the loss of the Collared Redstart.

• 

  Ant-plant coevolution: a systematic evaluation of the Myrmelachista haberi (Formicinae) and Ocotea sp. (Lauraceae) symbiosis, May 2009

  Murtaza Paghdiwala

  I have evaluated the relationship between Myrmelachista haberi and Ocotea sp. (Los Llanos) to provide definitive evidence supporting the nature of the symbiosis and possible explanations in terms of co-evolutionary history. This interaction has been described in terms of benefit to the ant-domatia and nutrition via phloem-feeder farming – but benefits from the plants perspective have gone largely unstudied. McNett (2009) attempted to quantify the nature of the relationship by monitoring the uptake and movement of stable isotopes through each of the three participating species. This study found that nutrients do not transfer between the organisms, but left the possibilities for alternative vectors of mutualism open. In our study I have systematically evaluated this interaction in terms of all conventional ant-plant services: (1) the tendency of the ants to clean the leaves of foreign (invasive) matter, (2) the foraging behavior of the ants, and (3) the effect the presence of ants has on herbivory and response to disturbance. Myrmelachista haberi do not remove foreign matter from the leaves, do not prefer to feed on the leaves, nor do they respond to herbivory damage on the leaves. My results provide definitive evidence supporting that the nature of the relationship is not a mutualism.

• 

  Captive breeding causes small body size in Morpho peleides limpida (Nymphalidae: Morphinae), May 2009

  Danny Goldish

  Captive breeding has many positive implications in terms of conservation, but when practiced irresponsibly, can result in harmful consequences like inbreeding. Inbreeding has been shown to result in developmental instabilities like small body size and fluctuating asymmetry. In this study, I used small body size as a proxy for inbreeding by comparing measurements of the butterfly Morpho peleides limpida from wild and captive bred populations in terms of right forewing and right antennae length. Both measures of size were found to be larger in wild populations than captive populations. The greatest variation in the means was observed in female right wing measurements, with larger mean lengths in wild populations (76.99mm ± 4.23mm) compared to captive populations (66.58mm ± 2.10mm). This shows that rearing techniques used in butterfly gardens may invoke varying amounts of inbreeding. New measures must be taken to practice more responsible breeding such as ensuring the introduction and maintenance of more genetic variation in captive populations.

• 

  Changes in altitudinal distribution of hummingbird diversity between forest and pasture habitats, May 2009

  Jessica Chute

  Climate change has affected the composition of bird communities elevationally in Monteverde, Costa Rica (Pounds et al. 1999). In addition, habitat transformation from forest to pasture has favored weedy species there (Feinsinger 1988). This study sought to combine hummingbird distributions across both habitat type and elevation, as the interaction of habitat disturbance and climate change is not well understood. Past studies have shown changes in hummingbird communities for either climate or habitat changes (Oliver 1993; Donnelly 1998; Smith 2000; Lynn 2001; Winchell 2001; Spear 2004). In order to observe these changes, I hung hummingbird feeders in different elevational zones in both forest and pasture. I found that Purple-throated Mountain Gems (Lampornis calolaemus) have shifted upward in elevation, and Violet Sabrewings (Campylopterus hemileucurus) and Green-crowned Brilliants (Heliodoxa jacula) show trends towards upward movement as well. Also, I observed that the communities of both fields and forest habitats have been altered. I saw no open-area specialist species, very low numbers of any species in pasture sites, and I did not observe some common forest species. My data suggest possible changes in the composition of the hummingbird communities of Monteverde.

• 

  Changes in female behavior in eusocial wasp Mischocyttarus mastigophorus (Hymenoptera: Vespidae) due to the removal of males from the nest, May 2009

  Elizabeth C. Feit

  Males of independent founding hymenoptera contribute little to the nest by not foraging for food or feeding larvae. Males are a potential cost to the nest because they consume resources and are not used for reproduction, but males of Myschocyttarus mastigophorus can be found on the nest year. To investigate if the behavior of females changes when the males are not present, baseline behaviors of both males and females were recorded for four nests M. mastigophorus, then the males were removed and observations continued. Baseline behaviors indicate that females departed (t = 2.33) and arrived (t = 2.81). Departures increased after the males were removed (t = 2.33, all p < 0.10) and there was a trend for females to arrive more frequently (t = 1.67, p = 0.14). Females possibly increased these behaviors to forage while the males are not present so the males cannot take food away from the females. It is possible that the males are present year round purely for reproduction with non-sibling females.

• 

  Eciton burchellii: polymorphism of submajor caste and foraging efficiency, May 2009

  Samantha Alger

  Due to the link between efficiency and fitness, there should be selective pressure for morphology and behavior that promotes foraging efficiency. Among social insects, selective pressures act on individuals, shaping the physical castes of a colony. The highly polymorphic army ant, Eciton burchellii, has castes with morphological adaptations to allow task specialization. This study investigates what selective pressures are acting to shape the polymorphism of the submajor caste in E. burchellii. Ants were collected to find a relationship between ant caste and the prey’s biomass, width, and length. Results show that prey width is the greatest pressure effecting transportation efficiency, and in turn, shaping the evolution of the specialized porter caste (i.e., submajor). Results also indicate that of all the castes, submajors are found to be the most morphologically different and they carry the most different sized prey. Possible explanations to Eciton’s physically exaggerated submajor caste include their outstanding need of transport efficiency and unique prey preferences.

• 

  Ecological footprints in Monteverde, Costa Rica, May 2009

  Sarah Ory

  In this study I calculated the Ecological Footprints of community members in three areas in the zone of Monteverde, Costa Rica. The three areas that I studied were San Luis/ Cañitas, Santa Elena/ Cerro Plano, and Monteverde. I presented a survey of 21 questions regarding a person’s environmental impacts in rural communities and more urban communities. I assessed the difference in Ecological Footprints, Carbon Footprints, Food Footprints, Housing Footprints, and Goods and Services Footprints between the three communities and determined no statistically significant differences. The mean Ecological Footprint in San Luis/ Cañitas was 8.12, Santa Elena/ Cerro Plano was 8.44, and Monteverde was 7.04. Additionally, I compared the footprints in the three communities with the mean footprints in Costa Rica as a country. Costa Rica’s mean Ecological Footprint (10.5) and Carbon Footprint (3.6) were significantly higher than those of the three communities I looked at in Monteverde. There were no significant differences between the Food Footprints and Goods and Services Footprints. I found that food consumption was the most influential factor in the Ecological Footprints in San Luis/ Cañitas, Santa Elena/ Cerro Plano, and Monteverde (48%, 52%, 49% respectively). The Housing Footprint was a higher percentage of the total Ecological Footprint in San Luis/ Cañitas (32%) in contrast to Santa Elena/ Cerro Plano (19%), and Monteverde (20%). The percentage of Goods and Services Footprint in the total Ecological Footprint was similar in San Luis/ Cañitas, Santa Elena/ Cerro Plano, and Monteverde (13%, 14%, and 14%, respectively). I also examined what percentage of people in each community finished primary school, high school, and university, as well as what percentage of people were from Monteverde, San Luis, other areas in Costa Rica, and areas outside of Costa Rica. Using the Ecological Footprint to determine the impact that a person has on the environment is extremely important in raising awareness through the knowledge of how each individual and their personal decisions can affect the environment. Through assessing different communities, understanding can be achieved as to how community dynamics and individual decisions can be utilized to improve human impact on the environment.

• 

  Effect of color and height on oviposition preference and attraction of volant insects, May 2009

  Emily Daniel

  Abundance of volant insects and aquatic larvae was investigated in relation to vertical stratification and color of either required resource or oviposition site within the understory at the Finca Cataracta, in San Luis, Costa Rica. Three insect traps were hung per tree (three trees total used) at heights of 8 ft, 4 ft, and ground level. Each platform at the respective height consisted of four bottles that were green, red, black, or clear. Oviposition in different colors by Ephydridae and Psychodidae was affected by height. Both larvae were most abundant at the bottom level, though Ephydridae showed significant preference for black, while Psychodidae was more abundant in clear. The attraction of flying insects to color varied with height. Each Order was collected in large abundance at a specific color and height when the factors were juxtaposed (Diptera- top, black; Coleoptera- middle, clear; Hymenoptera- bottom, green). This study reveals the importance of visual cues in relation to height for oviposition behavior and volant insects.

• 

  Effects of ultraviolet radiation and degraded water quality on growth and survival of Bufo marinus tadpoles, May 2009

  Brenna Levine

  Amphibian species worldwide are currently experiencing population declines and decreased ranges. This decrease in amphibian populations is due in part to habitat degradation such as canopy cover loss and decreased water quality. Other amphibian species, however, such as Bufo marinus, are experiencing population growth and global expansion. In this study, I tested the effects of loss of canopy cover and degraded water quality on growth and survival of B. marinus tadpoles by exposing them to conditions of elevated levels of ultraviolet radiation, degraded water quality, and a combination of these two factors. I found that B. marinus tadpoles have high survivorship and low rates of mortality when exposed to ultraviolet radiation and degraded water quality separately. When these two environmental stresses are combined, however, B. marinus tadpoles experience low survivorship and high rates of mortality. These results provide insight into why B. marinus is experiencing population expansions, population increases, and why it has become an invasive species in many countries while native anurans are going extinct.

• 

  Factors and impacts of ecotourism on revenue of private reserves in Costa Rica, May 2009

  Grace Heusner

  Tourism in Costa Rica represents a large piece of the country’s national revenue, but the exact funds private reserves obtain from this source has been insufficiently studied. The goal of this investigation was to determine reserves’ ecotourism revenue and factors impacting differences in income. Survey data was collected from 17 private reserves in Costa Rica to determine percentage of revenue derived from tourism, payments for environmental services (PES), and donations or other sources. In addition, the survey sought to identify factors that may explain differential revenues. An average of 88% of revenue came from ecotourism, 8%percent from donations, and 4% from governmental payments. There were significant correlations between marketing budget and revenue, as well as tourists per year on overall tourism revenue. However, size, distance from San José, and park admission fee had no significant correlation to tourist revenue, indicating that tourists visit reserves independently of these factors. Studies have hypothesized that ecotourism may not be an effective vehicle for conservation, and opinion results of the survey supported this belief. However, payments for environmental services may represent an economically viable way to balance the conflicts between tourism and conservation.

• 

  Guidelines for sustainable ecotourism in Monteverde, Costa Rica, May 2009

  Valerie Caldas

  Tourists are increasingly attracted to the world’s natural wonders (Honey 1999). The Convention on Biological Diversity (CBD) recognized that tourism can also negatively impact the natural areas and formulated guidelines for the proper management of ecotourism. Costa Rican tourism has experienced a boom in the past two decades, and one of its most popular destinations is Monteverde, an area composed of many private reserves. Eleven of these reserves were investigated using the guidelines provided by the CBD. It was found that Monteverde’s private reserves followed some guidelines, such as offering local employment, local access to reserves and following good waste management. However, there is not enough monitoring of biodiversity on the part of the reserves, many reserves do not have rules or regulations for tourists to follow, and a lot of reserves do not offer environmental education programs or community outreach. This study recommends that each reserve make a permanent plan outlying how it will protect biodiversity in light of increased ecotourism.

• 

  Human population density effects on soil nematode abundance and nitrogen levels, May 2009

  Sarah Hulick

  This study investigates the effects on human population density on soil properties and found significant effects in nematode abundance and soil nitrogen levels. Five locations with differing human population densities around Monteverde, Costa Rica were chosen for soil sampling to conduct chemical tests and microfauna extractions. Chi square test (p = 0.02) prove that the differing soil location caused changes in nematode abundance, and a regression between nematode abundance and soil nitrogen (R square = .96) proved a strong relationship between the two. From this study we can see the impacts of human disturbance on levels of nitrogen and nematode abundance within our soil systems.

• 

  Passiflora (Passifloraceae) defenses against Heliconius cydno (Nymphalidae: Heliconiinae) oviposition, May 2009

  Kim Khuc

  The purpose of this study was to determine the relative effectiveness of Passiflora defenses: elevated levels of cyanide, egg mimics, and variable leaf shapes, against oviposition from Heliconius cydno. The effectiveness of these defenses would reveal H. cydno’s preferences for oviposition sites and the primary criteria it uses when evaluating oviposition sites. Forty-two Passiflora oerstedii vines from the Monteverde Butterfly Garden, in Costa Rica, were divided into three treatments that added either cyanide, false eggs, or changed the shape of young leaves. Another twelve Passiflora coccinea vines were used in a second experiment that added false eggs to the young leaves, tendrils, and meristems. The results show trends that the various treatments deterred oviposition. Out of the 11 total eggs laid on leaves in the cyanide treatment, 82% of the total number of eggs was on the control leaves, then 9% on the methanol leaves and 9% on the methanol-cyanide leaves, indicating that the chemical cues from methanol discourage oviposition by H. cydno (!2 = 11.64, df = 2, p = 0.003). For the vines with false eggs, out of a total of 19 eggs, 68% of the eggs were on the control leaves (! 2 = 2.58, df = 1, p = 0.11). Lastly, the control leaves of the modified leaf shape experiment had 73% of the total number of eggs, 15, while the modified leaves had 27% (! 2 = 3.23, df = 1, p = 0.07). These trends show that H. cydno likely relies on chemical cues more than visual cues when choosing oviposition sites. In addition, the lack of evidence for larval cannibalism in H. cydno and its willingness to oviposit on multiple Passiflora species demonstrate that egg mimics and variable leaf shapes are less significant factors in oviposition decisions.

• 

  Repulsion from chemical cues in Bufo marinus (Cane toad) tadpoles, May 2009

  Brittany Kolehmainen

  Predator-prey relationships have been studied relentlessly throughout all different taxa and systems. Larval anurans use the mode of chemosensory to detect and avoid predation. By exposing Bufo marinus tadpoles to a variety of natural chemicals (crushed conspecific larvae and metamorphs, and crushed annelid prey) a strong repulsion was demonstrated. Avoidance of the treatments verified that Bufo marinus tadpoles are sensitive to changes in the chemical make-up of their environment that could be caused by a predator in close proximity.

• 

  The effects of active vs. natural reforestation on bird diversity, May 2009

  Jessica Springstead

  With rapid deforestation rates and loss of diversity the ability to reforest degraded landscapes faster than they would naturally regrow could be an effective tool for conservation. Many different methods of active reforestation have been proposed (Holl et al. 2000, Lamb et al. 2005, Martinez and Howe 2003) but because it is impossible to plant every species of plant that would be found in an area much of the diversity after planting must come from vertebrate dispersers of which most are birds (Fang and Peng 1997, Holl et al. 2000, Lamb et al. 2005, Martinez and Howe 2003). I wanted to know if active reforestation with trees whose fruits are normally bird dispersed affected the diversity of birds in that area. I observed birds in two areas of the Calandria reserve in Los Llanos, Costa Rica that have been reforesting for approximately nine years. One area was a naturally reforesting coffee plantation and the other a fallow pasture that has been planted with over a thousand trees. Using a Shannon-Weiner index and a modified t-test, I found that bird diversity was much higher in the pasture area than the coffee area. (H’Pasture= 3.419, H’Coffee= 1.192, p< 0.001; EPasture= 0.927, ECoffee= 0.370) Though there was high overlap of species between areas there were only seven species seen only in the coffee area while 22 were seen only in the pasture area. My results show that actively planting trees results in higher bird diversity than natural reforestation. Because the diets of many of these birds includes fruit and so they disperse seeds, it is also likely they will act as agents to increase reforestation even further.

• 

  The effects of Cecropia obtusifolia and Cecropia polyphlebia on lung capacity in relation to alkaloid concentration, May 2009

  Mai Lee Xiong

  For centuries, people have depended on nature to alleviate their ailments. A popular natural remedy for asthma is the use of Cecropia adenopus (Rivero 2008). In this study, I looked at two Cecropia spp., C. obtusifolia and C. polyphlebia, found in Monteverde, Costa Rica. Cecropia obtusifolia is found at lower elevation and has a mutualism with Azteca ants while C. polyphlebia is found at higher elevation in the Cloud Forest with no ant mutualism. A previous study by Ross (2003) found that ingestion of C. obtusifolia leaf decoction increased lung capacity by three to four percent compared to a placebo group. A possible reason is the presence of alkaloids (Schmeller & Wink 1998) in leaves of Cecropiaceae (Morton 1981). I predicted that since C. obtusifolia has a mutualism with ants, it would have less alkaloids compared to C. polyphlebia, thus rendering it less effective as an anti-asthmatic agent. I followed the protocols from Ross (2003) for tea preparation and lung capacity measurement and Gottheiner (1998) for alkaloid extraction. I found no increase in lung capacity from drinking Cecropia decoctions. The mean rate of change, which is the final lung capacity measurement minus the initial divided by the number of samples in a group, for the control is 0.136 L with a standard error of 0.066; C. obtusifolia, 0.180 L and 0.090; and C. polyphlebia, 0.172 L and 0.100 (one-way ANOVA; F2,52 = 0.056, p = 0.946). Further, while C. polyphlebia may have more alkaloids, this was not significant enough to make a difference in lung capacity.

• 

  The effects of elevation and land use on ant activity and ant species diversity, May 2009

  Laura Heil

  In today’s world, it is becoming increasingly important to understand the effects that humans have on Earth’s ecosystems. Approximately 39 to 50% of the Earth’s land has been transformed or degraded by human activity (Vitousek et al. 1997). Ten to fifteen percent of that land has been altered for row-crop agriculture or for industrial development and six to eight percent has been converted to pastureland. These transformations represent the leading causes of decreases in biodiversity. As a result, they alter the global biogeochemical cycles and have considerable effects on climate change. Humans contribute more and more everyday to climate change and it is known that many species are moving up in elevation in response to these changes. The purpose of this study was to examine the effects of elevation and land use on ant activity and ant species diversity. I recorded the time it took for ants to arrive at a bait trap on an elevational gradient (1000 masl, 1375 masl, 1550 masl, and 1800 masl) in forest sites versus pasture sites in the Monteverde area. Then, I separated the collected ants into morphospecies in order to calculate species diversity. I found that as elevation increases, ant activity and ant species diversity decreases in the pasture sites. Also, ant activity and species diversity were higher in the pasture sites than in the forests sites. These results indicate that elevation and land use affect ant activity and ant species diversity. Provided that ants are good bioindicators, elevation and land use also impact invertebrate activity and diversity.

• 

  The effects of farming practices on nectar quality and quantity in Coffea spp, May 2009

  Jennifer Carter

  In the developing world traditional low-input farming practices are being replaced with high-input practices as a way to increase yield. The environmental and economic impact of inputs has driven researchers to seek ways to minimize inputs while maximizing crop yields. In some crops, like Coffea spp., pollination plays an important role in yield. The purpose of this experiment is to compare nectar quality and quantity of Coffea flowers between low-input and high-input farms, demonstrating a link between practices, pollination, and crop yield. I found that more traditional, low-input practices have higher sugar concentration than high-input practices (t = 2.82; p = 0.006). The mean sugar concentration for the high-input practice is 27.9% ± 3.0 and for the Low Input practice is 29.8% ± 3.4. Although, there was no statistical difference between nectar quantities (t = 1.35; p = 0.19), there was a trend toward higher quantities in low-input practices. The mean quantity for the high-input practice is 0.047 ± 0.02 mm and for the low-input practice is 0.07 ± 0.13 mm. Though preference studies in pollinators, like honeybees, (Apis mellifera) show bees cannot distinguish between nectars of less than 4%, perhaps patches with higher quality nectars receive better pollinator service and impact farm yield. The more traditional, low-input farm has 2% higher yields. Though data suggest a link between management and nectar quality, further study is needed to more directly link reward, pollinator service and yield.

• 

  The effects of Xanthosoma spp. (Araceae) temperature, scent, and flowers on the mating frequency of Cyclocephala sexpunctata (Scarabaeidae), May 2009

  Sonia Lorraine Ghose

  Many pollinators have evolved very specified obligate mutualisms with the plants that they pollinate. One example of this kind of mutualism, in which the reproduction of both organisms relies on their relationship, is Xanthosoma spp. and Cyclocephala sexpunctata in Monteverde, Costa Rica. Xanthosoma spp. thermoregulate, attracting beetles because of a combination of heat, scent, and visual components of the inflorescence. The beetles crawl inside of the spathe and spadix inflorescence, where they both eat and mate. The specific stimuli that prompt the beetles to mate once inside the flower had not yet been widely examined. Through my experiments, I found that heat was the only factor that had a significant positive affect on mating frequency, as well as on the level of activity exhibited by beetles. The presence of flowers and the presence of scent did not have significant affects on mating frequency or activity. In addition, I was able to estimate that in a patch of 214 mature Xanthosoma spp., the population of males was about 200.6 individuals. About half as many females were captured, but an accurate estimate of female population could not be calculated because they were either not always present in inflorescences or they traveled farther to different patches more often than did males. These results add to a relatively small body of knowledge concerning this fascinating relationship between Araceae plants and their Scarabaeidae pollinators, and are important to understanding complex reproductive mutualisms.

• 

  The San Luis river continuum: a look at the chemical and biological changes along a longitudinal pristine river gradient, May 2009

  Kit Hamley

  From start to finish, physical changes along a river continuum create a natural longitudinal gradient to which biotic communities respond. This biotic response to natural physical change is a fundamental pattern of river ecology and is generally called The River Continuum Concept. The purpose of this study was to look at changes in water quality and aquatic insect communities along a pristine river continuum. Data was collected along a 1-kilometer series of 11 sites along the San Luis River in San Luis, Costa Rica. As expected, water quality did not change along the 1-kilometer reach. Overall percent abundances of insect Orders were different for each site. Three regions were created within the 1-kilometer continuum based on similarities in Shannon-Weiner values. Comparisons of these regions showed that percent composition of insect Orders fluctuate between the three regions. Water quality values were consistent over the entire continuum, therefore changes in biotic assemblages due to water degradation can be ruled out. This means that the changes observed in biotic assemblages were due to changes created by a natural longitudinal gradient.

• 

  Through the eyes of the locals: the role of ecotourism in the Monteverde region of Costa Rica, May 2009

  Jenna Diggs

  Identifying economic and environmental gains and losses from the ecotourism industry in the Monteverde region of Costa Rica is easy because these factors are well studied. Recognizing the influence of ecotourism over political, social and cultural factors of the region can be more difficult. One way to study all of these aspects is to gather information from the locals themselves. The majority viewed it as the most important industry and maintained that the natural and social environment had changed significantly in their time spent living in Monteverde. Also, their jobs depended on the industry. The participants in the study generally viewed ecotourism’s impact on economic, environmental, political, social and cultural factors of the Monteverde region as positive, but that does not discount opposing views. When asked how they would improve the industry, common responses included infrastructure improvement and planning, increasing tourist numbers, price reductions and promotion of education for locals and tourists.

• 

  Vocal signaling in Henicorhina leucosticta (Troglodytidae), May 2009

  Amber Desneige Fandel

  The communication between organisms has long been a fascination of mankind. Birds have been the subject of many such studies as they commonly have a large repertoire of communication techniques. This study examines the changes in several song measurements in order to determine the vocal responses of the breeding pairs to playbacks of various con-specifics. The researcher found that using measurements of low, high, center, maximum, and delta frequency of each pair before and after a playback, the pairs were easily differentiated from one another (Wilks != 0.61629, F20.455=3.57, p<0.001). Following playbacks, all pairs evaluated showed a decrease in maximum frequency of song phrases and a narrowing of frequency ranges (smaller delta frequency). Such changes in song characteristics may function to make the singing pair sound larger to intruders or to decrease call interference and the distance that the call travels.

• 

  A comparison of hemoparasite loads between bats (F: Phyllostomidae) of different feeding guilds in San Luis, Costa Rica, November 2008

  Rachael Zacks

  Bat hemoparasite studies have focused on bats as vectors for viruses that cause human diseases such as rabies, Ebola, and Henipavirus, while ectoparastite studies have looked at a broad range of ecological and abiotic factors that influence ectoparasite prevalence including age, sex, roosting ecology, and habitat. Yet diet had been largely ignored in both hemoparasite and ectoparasite studies. In this study, I looked at diet as a possible factor in hemoparasite load and also looked at the relationships between hemoparasites, health (with weight as a proxy), and ectoparasites. Four guilds were compared, sanguinivores, omnivores, frugivores, and nectarivores, with an overall sample size of 27 bats in San Luis, Costa Rica. I found differences in hemoparasite loads between guilds (Chi square test, p = 0.0026, x2 = 16.295, df = 4) and that bats with ectoparasites were more likely to have a small number of hemoparasites (Chi square test, p= 0.0004, x2 = 18.104, df = 3). Interesting facets to the study included the observation that frugivorous bats had the highest hemoparasite loads, including hemoparasites from all three categories studied (Plasmodium, Babesia, and unknown), and nectarivores had no hemoparasites but the highest percentage of ectoparasites. Interspecific competition between ectoparasites and hemoparasites, roosting ecology of the most common fruit bat, Artibeus toltecus, and coevolved immune signaling molecules may explain these new trends. Overall, the study introduced diet as a possible factor in hemoparasite load due to diet differences altering blood proteins that could promote hemoparasite immunity, but sample size limits the conclusiveness of the study. Future studies should further analyze these differences in the blood and include a broad sample size for each feeding guild, for the results could show the effect of diet on health, both in bats and humans.

• 

  Asymmetry of floral structures and the possibility of self-pollination in Oerstedella exasperata (Orchidaceae), November 2008

  Lindsay Brownell

  The purpose of this study was to investigate the causes of the pervasive asymmetry found in the neotropical orchid Oerstedella exasperata. Previous studies have found that high levels of asymmetry decrease reproductive success, and can be caused by a high amount of homozygosity within a population. This study tested the ability of O. exasperata to self-pollinate, a condition that indicates the possibility of a high level of homozygosity. In addition, the relationships between three degrees of asymmetry and floral color, floral mass, plant size and sun exposure were investigated to determine whether higher asymmetry is correlated with lower reproductive success or reduced overall plant fitness. Results showed an overall trend suggesting that self-pollination is possible, which implies that O. exasperata’s high level of asymmetry could be caused by homozygosity. Floral asymmetry was not related to any of the other examined factors, implying that it is a neutral trait that does not affect the overall fitness of this species of orchid. These results contradict other studies’ findings that asymmetry is detrimental to plant health, indicating that O. exasperata could be an exception to the general rule that symmetry indicates superior genetics in plants.