Monteverde Institute: Tropical Ecology and Conservation

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  Subcaste composition in responses to alarm and non-alarm pheromones on foraging trails of leaf-cutter ant Atta cephalotes (Hymenoptera: Formicidae), November 2010

  Michael Marquis

  The response of the leaf-cutting ant Atta cephalotes to its alarm pheromones from crushed heads were compared to its response to crushed bodies without heads in order to examine the relative subcaste (minor and forager) composition of the responding individuals. The percentage of minor workers responding to the body parts near the foraging trail were recorded and compared with the experimentally determined percentage of minors in the trail traffic. The average percentage of minors in the ants responding to the two treatments (Heads: 44.9±0.72%, Bodies: 38.8±0.77%, N = 1300) both differed (p = .0007, p = .0113, df = 1) from the baseline trail composition (22.3±0.51%, N = 405), but did not differ from each other (p = .382, df = 1). There was a difference in the strength of the reaction over time between the heads and bodies for both minors (p < .0001) and foragers (p = .004), suggesting a difference in stability between the pheromone types. The unexpectedly strong reaction by minors to crushed bodies calls into question the validity of previous conclusions regarding the role of minor workers in foraging trails, especially considering the proportional equality of minor reactions to alarm and non-alarm pheromone sources.

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  The effects of phosphorus, copper, and plant age on mycorrhizal abundance in orchid roots, November 2010

  Nathan Jespersen

  Mycorrhizae increase growth and nutrient acquisition in orchids. I study which factors affect mycorrhizal infestation. I organized three experiments: the first used wild orchids assumed to already be colonized by mycorrhizae and tested how receiving a nutrient solution that emphasized phosphorus affected mycorrhizae abundance. The second tested this same hypothesis with the exception that plants were initially devoid of mycorrhizae. It also tested how adept plants with and without mycorrhizae were at absorbing heavy metals such as copper and manganese from the soil to determine mycorrhizae’s remediation abilities. The third experiment focused on how age differences of plants affected mycorrhizae abundance. Roots were stained with Trypan Blue and mycorrhizae were then counted under a microscope. Wild orchids showed no difference in mycorrhizae with or without NPK spray (NPK = 13.33 +/- 11.2 VAM, water = 12.9 +/- 13.5 VAM). Lab orchids initially devoid of mycorrhizae, showed that there was a trend for NPK orchids to have fewer hyphae than those offered only water (NPK = 10.7+/-11.9 mycorrhizae, water = 18.3+/-29.2 mycorrhizae), although it lacked statistical significance (p = .12). The second part of experiment two showed that plants with mycorrhizae did have the potential to reduce heavy metals in soil because the orchids with mycorrhizae had 2.1 ppm of copper left in their growth substrate whereas the group devoid of mycorrhizae had 5.99 ppm. The third experiment found that orchids have consistent numbers of mycorrhizae at different life stages (young = 7.5+/-4.83 mycorrhizae, middle aged = 5.8+/-4.36 mycorrhizae, old = 8.8+/-6.76 mycorrhizae). Mycorrhizae abundance appears to vary greatly between individuals and infestation is not decided by a single factor.

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  Upslope movements of bird species in four life zones in Monteverde as a result of directional climate change, November 2010

  Kristina Bartowitz

  Directional climate change has shown upslope movements of bird species in both observational studies and theoretical studies in the Monteverde Cloud Forest, Costa Rica. However, this phenomenon has not been studied in great detail. In order to fully understand the effects of climate change on species composition, more thorough observation must take place. This study attempts to record the composition of bird species in four life zones in Monteverde. These results were compared to compositions of 17 years ago in the same life zones to determine changes in species composition. Mist netting and point counts observed 94 bird species total. Of the 94 species, 26 species had moved upslope from lower elevations, 5 species moved downslope from their original ranges, and 63 of species identified stayed in their original ranges. My findings show that there is a significant percentage of upslope movement in the birds of Monteverde. There is a need for more comprehensive observational studies of upslope movements in birds in tropical montane habitats to determine higher resolution elevational ranges in order to develop and implement successful conservation methods.

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  Vesicular-Arbuscular Mycorrhizae (VAM) spore abundance and soil characteristics along a neotropical premontane forest successional gradient, November 2010

  Kristin Schroder

  Tropical soils are generally nutrient poor, though they support high biodiversity and productivity. Most tropical plants are able to thrive in these soils because they form a symbiosis with Vesicular-Arbuscular Mycorrhizae (VAM). VAM increase the nutrient-absorption capabilities, and therefore the fitness, of the host plant. Previous studies suggest that as a pasture is allowed to regenerate, the soil should become less compact, more nutrient-rich, and the pH should become more neutral. These soil characteristics, in conjunction with spore number, may drive the rate and direction of some successional communities following disturbance. This study examines how VAM spore abundance, macronutrient levels (nitrogen, phosphorus, and potassium), bulk soil density, and pH change between plots at various stages of regeneration from pastures (ages 0-45, and primary forest, N=15) in the Premontane Wet Forest near San Luis, Costa Rica. The data show substantial variation within and between sites in spore number and other soil characteristics. For instance, the three pasture sites sampled varied from 4 to 83 spores (± 28), with nitrogen levels from 16.81 to 46.7 kg/ha (±16.46). Within each individual site there was also variation: the 25 year old forest ranged from 46 to 132 spores (± 45). Regeneration age did not significantly affect VAM spore number, macronutrient levels, or bulk density, though pH was positively correlated with increasing site age. Spore abundance was not significantly affected by variations in the other soil characteristics. These findings suggest that VAM spores may not be evenly distributed throughout the soil, instead having patchy distributions determined by soil heterogeneity and location of mycotrophic hosts. VAM do not appear to be limiting in the young pastures of San Luis, suggesting that VAM are unlikely to direct forest regeneration.

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  Age and sex-related activity in white-nosed coatis (Nasua narica), August 2010

  Rachel Munro

  The time allocation theory mentions that sociality increases an individual’s fitness because it cannot efficiently forage and watch for predators at the same time on its own, but if in a group vigilance can be shared and time to forage and participate in other activities can be increased, therefore increasing fitness (Caraco, 1979). White-nose coatis,Nasua narica, (Procyonidae) are diurnal and social mammals. Adult females and juveniles live together in bands whereas males are solitary and only join a band when mating. Because and individual cannot perform two activities at once, I studied how age and sex influence how coatis spend their time. I predicted that females would spend the most time as vigilance to protect their young, juveniles would spend the most time foraging to increase growth, and males would spend less time watching out for predators and more time foraging because predators are not as big a threat to them. A band of between 10 and 14 and several males frequented a garbage pit close to the Estación Biológica, Monteverde, Costa Rica. I recorded each individual’s behavior every minute. Adult females, adult males, and juveniles were recorded foraging, fighting, playing, grooming, climbing trees, resting, looking around (vigilance), and staying out of view (out of sight). A chi-square test was used to show that females were the most vigilant (32%) and that males foraged the most (60%). A large amount of time was spent in trees by females (30%) and juveniles, (56%) but not by males (4%). There were low observations of coatis fighting (4%), playing (3%), grooming (1%), and resting (1%). The chi-square test showed that all of the activities that the coatis participated in, and the amount of time they spent was significantly different. The results conclude that females are more vigilant to protect their young from predators. Males will spend more time foraging. And juveniles will spend the most time in trees to avoid predators, and foraging to increase growth.

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  Are native plant gardens better for conserving bird populations than gardens with exotic plants?, August 2010

  Jessica Ann Gouveia

  Loss of species habitat due to rapid deforestation of the Earth’s forests is a pertinent and serious problem. This issue especially affects birds. One way in which scientists and conservationists have suggested people could help conserve bird populations is by gardening. Many horticulturalists want to bring in ornamental exotic species of plants, however, it is believed by some that they offer little contribution to a functional ecological system; they do not harbor as many insects, nor do they have an ecological history with the birds of the native habitat. In this study, I examine the issue of whether native plants offer better habitats for bird conservation by comparing the birds that visit the native garden at the Biological Station of Monteverde (EBMV), an exotic garden at Los Pinos, and a mixed species garden at El Bosque. After comparing the different birds that visited each of these gardens and dividing them into categories based on their preferred habitat, I did not find a difference in the number of species that visited each garden, but I did find a difference in the type of species that I found. Overall, I found that the native plants support bird populations with more specialized habitats better than exotic plants do.

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  Comparison of abundance of vesicular-arbuscular mycorrhizal fungi on sun- and shade-grown coffea arabica plants, August 2010

  John A. Colantonio

  Large-scale coffee agriculture can have significantly detrimental effects on the environment. However, organic coffee production lowers these impacts and helps to conserve tropical diversity by reducing need for soil inputs. Natural, healthy soils contain beneficial vesicularmycorrhizal (VAM) fungi. These fungi help cycle nutrients, and support plant health and growth. Mycorrhizal mutualisms are abundant and effective in particular habitats, particularly those in which the fungi do not exhaust carbon resources for the plant. This study compares the abundance of VAM fungi vesicles on the roots of organic shade-grown coffee plants and those grown in the sun. Root samples were collected from an organic coffee farm and stained, and observed under high-power magnification to determine quantity of fungi vesicles. Data show no statistical significance in the mean number of vesicles between the two sample populations. This result implies that sunlight is not the only factor determining plant health and need for soil inputs.

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  Comparison of nest predation in two riparian habitats, August 2010

  Alexandra Kaye

  Clearing of riparian habitat in Monteverde, Costa Rica is prohibited up to 50 meters from the bank of the waterway. Unfortunately, this regulation is often disregarded, and forests bordering streams are cleared for a variety of purposes. Deforestation creates edge effects where there once was continuous forest, and it has been shown that rates of avian nest predation are higher on forest edges. In this study, I examined the proportions of eggs removed or damaged from artificial nests in four riparian habitats. Two of the chosen sites were forested, and two had been cleared for human use. The artificial nests contained two quail eggs and four clay eggs. The study lasted nine nest nights, and after the morning of each I returned to the site to census the nests and collect any bitten clay eggs for predator identification. I found no significant differences among predator types in the four sites. Contrary to my expectations, though, I found that the site with the greatest proportion of eggs removed or damaged was a forested site. The second forested site and one of the deforested sites were comparable in terms of nest predation proportions. The results of my study did not support my predictions that, in deforested sites, both nest predation and the incidence of bites by predators that thrive in human-modified habitats – coatis and opossums among them – would be significantly higher. Nonetheless, both the use of artificial nests and predators’ search behavior modification in response to high frequency of occupied nests may have affected the results of this study. Future studies should concentrate on these two factors before reaching any conclusions on the impact of riparian deforestation on avian nest predation.

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  Ecotourism, environmental awareness and green living in Costa Rica, August 2010

  Alexandra Sanserino

  Over the past 30 years, Monteverde, Costa Rica, has adopted ecotourism as its primary source of revenue. Since the inception of ecotourism in tropical regions, many studies have been done on both the positives (more conservation) and negatives (littering, pollution, etc.) associated with it. With the knowledge of both the benefits and consequences associated with ecotourism, the government of Costa Rica has adopted an environmental education program to make residents aware of environmental issues and give them the tools to protect the environment through their daily activities. But just how effective is this program? The current study compares environmental awareness and green living for two communities in Costa Rica: Monteverde and Las Juntas, a similarly sized community with little or no ecotourism. Surveys of 66 people in Monteverde and 30 people in Las Juntas were performed. Overall, there was a significant positive correlation between scores for environmental awareness and green living for Monteverde. Participants were then placed into groups based on their age, occupation and level of education for Monteverde. There was no significant difference between age groups in environmental awareness, but older people (over 36) showed to be more significantly green (mean ± sd = 7.63 ± 36.8)compared to the young (13-21) age group (mean ± sd = 3.65 ± 30.2). Likewise, participants who worked in ecotourism-centric settings (mean ± sd = 8.63 ± 2.26) were statistically greener than those who did not (mean ± sd = 5.72 ± 4.91). There was no significant difference between participants of differing education levels. Combining all participants for each community, there was no significant difference between ecotouristic Monteverde (mean ± sd = 7.01 ± 4.12) and Las Juntas (mean ± sd = 8.48 ± 5.01). Therefore, despite the fact that those who work directly in ecotourism score higher in both awareness and green living, Monteverde does not have a stronger environmental culture. This suggests that ecotourism is limited at instilling environmental knowledge and values. That, and the fact that Monteverde youth score lower in green living than older people, suggests a need for strong environmental education, even in communities where ecotourism is the foundation of the economy.

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  Effect of color and territoriality on hummingbird visitation to feeders in Monteverde, Costa Rica, August 2010

  Tiffany Reeves

  Many plants evolve to specialize in attracting hummingbirds by using color, timing, and flower shape. Depending on the quality and quantity of flowers some species of hummingbirds become very territorial and protective of the area. Using three different colors, I studied which color was preferred by the hummingbirds and if there was a preference in the position of the feeder. A common belief is that red is the most favored color of hummingbirds. Another factor observed was territoriality. Its effect on other hummers’ visitations and color preference was noted. The movement of feeders and territoriality was also studied. Only one species significantly preferred red, while the others did not have a significant preference between red and white. Blue was disfavored, possibly due to its visibility in contrast with green. A dislike of the center feeder over the left and right feeders was also discovered, most likely due to the vulnerability of the location. The territorial bird pushed the other birds to the inside of the forest, and all of the feeders on the forest edge were still protected after an alteration in location.

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  Importance of flower size and yellow coloration as influencing factors in the reproductive success of Pleurothallis sanchoi (Orchidaceae), August 2010

  Elizabeth Ott

  Reproductive success can be linked to pollination success because pollination is needed for plants to reproduce and put out seeds. Factors that affect pollination success include color, nectar, scent, flower shape and size. Past research on Pleurothallis sanchoi has indicated that of the three color morphs, yellow, purple, and yellow with purple petals (YPP), yellow is the most attractive color. This study examines the importance of flower size and color in attracting pollinators in P. sanchoi. A total of 51 individuals were observed and the number of days required for pollinia removal was noted. The flowers were measured with a caliper for length. In the purple flowers, the amount of yellow area was measured by using a pinhead to estimate the overall yellow area. Color and length were significantly correlated, with yellow flowers being the smallest and purple flowers being the biggest. Pollinia removal was significantly correlated to color and was fastest in YPP flowers and slowest in purple flowers, although yellow flowers showed nearly equivalent rates to YPP flowers. The relation between flower length and days required for pollinia removal was not significant, as well as flower length and amount of yellow in purple flowers. It appears that yellow flowered plants have a slight reproductive advantage. YPP and purple flowers may be maintained in the population if more than one species are the pollinators for P. sanchoi and have different pollinator preferences or if these color morphs influence pollinators through scent or nectar.

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  Inflorescence size and butterfly visitation in Lantana camara (Verbenaceae), August 2010

  Calli Thompson

  Pollinators greatly influence the fitness of most tropical plants, and how effective plants are at attracting pollinators is key to their success. This investigation focuses on how inflorescence size of Lantana camara affects butterfly visitation. Naturally occurring inflorescence size was determined by counting how many flowers per inflorescence and how many inflorescences were in bloom per branch. The average number of flowers per inflorescence is 37 and the average number of inflorescences in bloom per branch is 2. To assess the impact of inflorescence size on butterfly visitation, five different sizes of L. camara inflorescences were created by bundling from one to five inflorescences, ranging from an average of 36 to 208 flowers per bundle. Butterfly visitation to each of these was recorded during sunny periods in the Monteverde Butterfly Garden, Monteverde, Costa Rica. As the size of the inflorescence increased, so did butterfly visitation. However, the proportion of butterfly visitors to number of flowers decreased as inflorescence size increased. Other traits (morphology, plant vigor, scent, etc.) impact attractiveness to butterflies. What is the point of the previous sentence? The interaction and balance of these other traits along with inflorescence size would reveal interesting results about how angiosperms create attractive inflorescences.

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  Leaf toughness and cyanide defense of Passiflora dioscoreifolia in varied light habitats, August 2010

  James Bellush

  Coevolution can lead to complex biological relationships between tropical plants and herbivores, as with Passiflora (Passifloraceae) vines and heliconiine butterflies (Nymphalidae: Heliconiiae). Constant herbivory from heliconiine butterflies has led to the development of cyanide-based defensive compounds by Passiflora, in addition to the more general defense of toughening leaves, found in all plants. To observe the effect of light availability on leaf toughness and cyanide content in Passiflora dioscoreifolia, leaves from twenty plants in sun and shade habitats were sampled in the forests of Monteverde, Costa Rica and tested for their leaf toughness and cyanide content. Plants in the sun habitat possessed more expensive defensive compounds, such as lignin and cellulose. Plants with a reduced photosynthetic capacity in the shade habitat possessed less costly compounds, such as cyanide. Leaves are tougher in sun habitat plants, providing protection against all herbivores, including Heliconius. Shade habitat leaves are less tough, thus requiring additional cyanide for protection. Resources, such as light, impact allocation of resources for defense compounds in the dynamic coevolutionary relationship between Passiflora and Heliconius.

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  Niche portioning in four frugivorous neotropical bats: Carollia subrufa, Carollia perspicillata, Sturnira ludovici, and Artibeus toltecus, August 2010

  Gregory Pavur

  Neotropical bat diversity is high, suggesting finely partitioned niches. Mist nets were set up on edges of Premontane Moist Forest and secondary forest remnants of San Luis, Costa Rica to examine plant use by frugivorous bats there. I caught 42 frugivorous bats of four species and one nectavorous bat: Carollia subrufa, Carollia perspicillata, Sturnira ludovici, Artibeus toltecus, and Glossophaga soricina . The number of Piper, Solanum, and other seeds were counted and identified in fecal matter to see what each species of bats were eating. The main diet of all 4 species of bats studied consisted of similar species of Piper. Although A. toltecus is known to have a diet consisting of mainly Solanum (Dinerstein, 1981), I found that every A. toltecus fecal sample had only Piper. Though Piper species were not distinguished from one another, their general morphology and accessibility to bats suggest that bats are not partitioning niches. Instead, all four sympatric bat species seem to be eating the same thing. It could be that all four of these species could coexist because there is an abundance of Piper in the area at present. Because area plants have complex seasonal flowering and fruiting phenologies, the study might have to be repeated at a time of resource depletion to see possible niche partitioning.

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  Species richness of epiphytic vascular plants living on Catura and Híbrido coffee varieties in San Luís, Costa Rica, August 2010

  Trevor Biggs

  Coffea arabica is a widespread crop, existing both in monocultures as a cultivated variety of tree and in mixed organic farms in numerous varieties. This study takes place on an organic farm where the varieties host diverse species of vascular epiphytes. This study compares the species richness of vascular epiphytes on trunks and stumps of the cultivated variety known locally as caturra and also several closely related traditional varieties collectively known locally as híbrido. Results show that exposure to sunlight was significantly more influential than the type of coffee variety in determining the average richness per tree. However, the caturra cultivar thrives under full sunlight, whereas híbrido cultivars do best with shade, possibly allowing caturra to be better hosts for vascular epiphytes. Other studies state epiphyte species richness increases with tree size. Tree size was not a variable in this study, but this would be a good idea for further study.

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  Structure and function of buttress roots in tropical oaks of Quercus spp. in windward and leeward cloud forest, August 2010

  Bridget Johnson

  Buttress roots of tropical trees are widely accepted to function in structural support, yet there is no current consensus about the processes that govern their formation. This study aims to determine if wind is a driving force in influencing the structure and function of the buttresses of Quercus spp. (Fagaceae) in Monteverde, Costa Rica. Two sampling sites of dissimilar wind exposure were designated. The first was a highly windy habitat at the ridge of a mountain. The second was at a lower elevation in the mountain’s shadow, which experienced less intense winds. Thirty-one adult individuals from the two locations were sampled for buttress frequency, height, length, thickness, and curvature on the windward and leeward sides of each tree. No significant trends were found between the buttress measurements and either location or species. Two nearly significant results were revealed regarding the ratio of leeward-to-windward buttress thickness and leeward buttress curvature. However, these results were contradictory and did not support the hypothesis of wind being the primary factor in determining buttress structure. Instead, it is likely that the formation of buttresses is a complex and multi-faceted process, and that wind is one of numerous ecological components that influences buttress structure.

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  The effect of whey on the growth and survival of Isthmohyla pseudopuma tadpoles, August 2010

  Patricia L. Stamper

  Water contamination and poor water quality in general have escalated in recent years. Streams and rivers located near dairy farms are commonly polluted by a byproduct of cheese making,whey. Due to factors such as water degradation, amphibian species have been experiencing rapid population declines worldwide. The purpose of this study was to determine the effects of whey waste on Isthmohyla pseudopuma tadpole growth and survival. It was found that whey waste generally has a negative effect on I. pseudopuma tadpole survival and little effect on the growth. Additional observations such as metamorphosis were observed towards the end of the experiment, further research should look into rate of metamorphosis and development of deformities (if any) due to the presence of whey waste.

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  The mosaic effect habitat fragmentation and microhabitat partitioning among three wren species in San Luis, Costa Rica, August 2010

  Mackenzie Most

  Increasing human presence in previously forested areas leads to the alteration and fragmentation of habitats used by resident species of birds. In this study I examine the effects of a mosaic-like arrangement of habitat types on the abundances and distributions of three species of wrens, the House Wren (Troglodytes aedon), Plain Wren (Thryothorus modestus), and Rufous-and-white Wren (Thryothorbus rufalbus) to determine any resulting differences in abundances and distributions between species. I conducted visual and auditory observations of wrens during timed walks through four habitat types in the San Luis valley of Costa Rica including primary forests, secondary forests, disturbed home and garden areas, and cleared pastures. Wrens were observed to partially overlap in range likely due to factors of proximity and niche partitioning on the basis of overall habitat, microhabitat, and edge characteristics, but not tree height. Overall wren abundance was equal between species but differed between habitats, and abundance was higher in disturbed areas with high heterogeneity than in homogeneous disturbed areas. Effects of human disturbance are thus demonstrated to vary based on structural characteristics in terms of species response.

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  The role of size, social interaction and predation on metachrosis of the green spiny lizard (Sceloporus malachiticus), August 2010

  Daniel Whonsetler

  Metachrosis, or color change, in lizards may have social or antipredator functions. The purpose of this study was to determine impact of size, social interaction and predatory pressures on metachrosis in S. malachiticus. Nine lizards were collected and photographed to quantify their initial color. The snout-vent length and photographed color (as hue, saturation and brightness) were measured and compared (Spearman Rank Correlation, P > 0.60), showing no significant correlation. Lizards were then paired and allowed to interact for thirty minutes, once with every lizard and photographed after. Interactions were broken down into three groups (same size, with larger, with smaller), where color after interaction was compared to initial, showing significance only for increasing hue and decreasing brightness for individuals interacting with smaller lizards (Paired t-test, P < 0.015). Lizards were also handled for 15 seconds to imitate predation. Before and after photographs were compared, showing a significant decrease in brightness (paired t-test, p <0.0001). Lizard darkening during predator imitation trials provides more evidence for thermoregulation and possibly crypsis, while changes in color during social interaction suggest selective pressures beyond thermoregulation for color change. Therefore, metachrosis here is not just a response to temperature and light, but also suggests that interactions and stress contribute to this phenomenon.

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  The use of macroinvertebrates as water quality indicators along two streams in a disturbed landscape in Cañitas, Costa Rica, August 2010

  Emily Thorpe

  Human alteration of natural landscapes often has significant impacts on nearby aquatic ecosystems, affecting both abiotic and biotic factors. Water quality testing has primarily depended on the monitoring of abiotic factors; however, the use of biotic indicators has emerged as a valuable tool. This study looks at the water quality of two joined streams in Cañitas, Costa Rica, a region dominated by coffee and dairy production. The abiotic indicators measured included dissolved oxygen, temperature, nitrogen, phosphorous, pH, and turbidity. Macroinvertebrates were sampled as the biotic indicators. Principal Components Analysis was used to determine the similarity between sites. Based on BMWP’-CR scores, one site had bad, very contaminated water quality; six sites had bad quality contaminated water; and three sites had water with regular quality, eutrophic, medium contamination. There were no significant correlations between the biotic and abiotic indicators of water quality. BMWP’-CR scores were significantly correlated with S and H’; indicating that as S and H’ increased, so did BMWP’-CR. This study indicates that human alteration of natural landscapes is likely affecting aquatic ecosystems and the macroinvertebrates that inhabit them; however, because there are no correlations between biotic and abiotic factors, it cannot conclude how exactly these alterations are affecting them.

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  Abundance of arbuscular mycorrhizae in epiphytic Orchidaceae: abiotic, biotic and taxonomic factors, May 2010

  Logan E. Smestad

  Despite nutrient stress, not all epiphytes have mycorrhizal associations, including some epiphytic orchids (Lesica & Antibus 1990). In this study epiphytic orchids were collected from tree and limb falls in the Monteverde Cloud Forest, Costa Rica. Abiotic factors such as branch circumference, presence or absence of moss mats, thickness of moss mats, substrate pH and moisture content were measured for their impact on mycorrhizal abundance. Biotic factors such as relative age of the orchid, plant height and the presence or absence of pseudobulbs were also considered. Finally, taxonomic factors were assessed as abundance of mycorrhizae related to the Pleurothallid or non-Pleurothallid subtribes. Unlike Lesica and Antibus (1990) who found less than half of the collected Orchidaceae species with mycorrhizal associations, I found them to be nearly ubiquitous. Of the 50 samples taken from a variety of orchid species, 46 of them showed mycorrhizal associations. Abiotic factors, taxonomic factors, age of the orchid, and plant height had no obvious bearing on mycorrhizal abundance. However, orchids with pseudobulbs had fewer mycorrhizal hyphae. Therefore orchids lacking mycorrhizae may compensate with features like pseudobulbs, which store nutrients, but their near ubiquity suggests that most orchids rely on mycorrhizal fungi to increase nutrient uptake.

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  Analysis of resource allocation trade-offs dictated by deceit pollination strategy in the monoecious understory shrub Begonia cooperi (Begoniaceae), May 2010

  Gracy L. Huntley

  There is little information in the literature describing the species Begonia cooperi yet it shares a similar morphology and pollination strategy with Begonia involucrata, a species well studied in the region of Monteverde, Costa Rica. The objective of this study was to examine the focus of energy allocation to reproductive function in B. cooperi andvalidate past data indicating that directional selection drives female flowers to be larger than males. Fifty independent B. cooperi inflorescences were measured and fecundity was calculated for thirty-seven out of the fifty. Results indicated that there is not a direct trade-off between female flower number and mean female sepal size per flower per plant, and a significant positive correlation was found between percent fruit production and estimated female flower number. These results indicate that there may be more than two variables influencing the plants energy prioritization towards female reproductive function. Knowing more about interspecific differences amongst Begonias using deceit pollination helps one better understand the coevolutionary cycle of pollinator pressures and optimal floral characteristics.

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  Anthocyanins and delayed greening: Inhibition of leafcutter ants (Atta cephalotes) in Inga punctata (Mimosaceae) and Zygia palmana (Fabaceae), May 2010

  Antoinette Hertel

  Leaves that undergo delayed greening with anthocyanins are suspected of having antiherbivore defenses in addition to low leaf nutrient content. This study examines two species with delayed greening, one with anthocyanins, Zygia palmana, and one without, Inga punctata, to determine whether anthocyanins deter herbivores more than low nutritional quality. Leaf samples were taken from 20 trees in Monteverde, Costa Rica. Chlorophyll a, chlorophyll b, carotinoids and anthocyanins were extracted from leaves and tested for concentrations as well as chemical preference to an herbivore, Atta cephalotes. There was a significant preference for older, fully green leaves in each species (p=.041), as well as a preference for the young leaves of Z. palmana that have little anthocyanins (p=.0009). This suggests that, while leafcutters prefer older leaves with higher nutritional content, anthocyanins further help to deter herbivores from attacking young leaves.

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  Arbuscular mycorrhizal fungi vesicles in Coffea arabica (Rubiaceae): Agroforestry and conventional coffee farms, May 2010

  Jason C. Kopp

  Due to their nutrient-poor soils, a pressing issue in tropical countries is the conservation of land through more sustainable agricultural practices in order to continue to feed their booming populations. Agroforestry is a possible sustainable solution, which reduces negative impacts on the environment, including impacts on mycorrhizal fungi. Mycorrhizal fungal associations within plants are important designators of a healthy crop and a more sustainable management system. This study investigates differences in arbuscular mycorrhizal fungi (AMF) vesicle abundance between the center and edge of an agroforestry coffee farm and the center of a conventional coffee farm. Eight different root samples were stained from each of the three locations using Trypan Blue (24 total root samples). The number of vesicles were then counted in three root segments from each of the 24 samples, and averaged for each location. Results showed a marginally statistically significant difference between all three locations (ANOVA, F=3.31, p=0.05, df=23). In addition, the center coffee plants in agroforestry had more AMF vesicles per root segment (28.04 ± 9.38 std) than roots at the center of conventional coffee (12.96 ± 11.23 std) and were statistically different; but neither were statistically different from coffee at agroforestry edge (21.17 ± 14.08 std; Tukey's Multiple Comparison, q=2.52, p<0.05). Although there was little difference in AMF vesicle abundance on a micro-scale within the agroforestry farm, there were more vesicles than in conventional coffee production. This could be attributed to the use of biological fungicide, greater moisture retention, or younger trees in the agroforestry farm.