Monteverde Institute: Tropical Ecology and Conservation

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  Nesting behavior in the resplendent quetzal (Pharomachrus mocinno: Trogonidae), June 2006

  Amber Carr

  The Resplendent Quetzal (Trogonidae) lives in the cloud forests of Central America. In Costa Rica, nest boxes have been placed in the Monteverde Cloud Forest Preserve to increase the population sizes of these birds, which are listed as near threatened by C.I.T.E.S. Cameras placed inside the boxes from 2000 to 2003 as web cams and captured stills inside the nests. I used these four years of captured images and made external observations of two nests to study if there were differences in parental investment for incubation and rearing. I found evidence that 1. During incubation the female spent more total time in the nest than the male (Nest 2 tied p-value =0.0001). 2. The male had significantly more visits per day during incubation than the female (Nest 3 tied p-value =0.0360 and Nest 4 tied p-value =0.0391). 3. The female had significantly more visits per day during rearing than the male (Nest 1 tied p-value =0.0209). 4. The female and male had significantly more total time in the nest for incubation than rearing (Nest 1 female tied pvalue = < 0.0001 male tied p-value =0.001 and Nest 8 female tied p-value =0.02853 and male tied p-value = <0.001) and the mean visits were significantly higher for incubation than rearing for both males and females (Nest 1 female tied p-value =<0.0001 and male tied p-value = < 0.0001, Nest 6 female tied p-value = 0.0315, and Nest 8 female tied p-value = 0.0285 and male tied p-value = < 0.0001). 5. The female had a significantly higher number of visits to the nest during rearing than incubation (Nest 1 tied p-value =0.0097 and Nest 6 tied p-value =0.0031). These results suggest that the female invests more in the young than the male. The female might be willing to invest more in her young due to the fact that she initially invests more in her egg than the male does in his sperm. The study of the nesting behavior of these birds is important to their conservation. Fledging success of their young will be what determines whether their populations will be threatened by extinction.

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  Permaculture garden design for the cloud forest school-the Centro de Educación Creativa, June 2006

  Lauren Fifield

  This is a proposal for the creation of a permaculture garden at the Cloud Forest School- Centro de Educación Creativa (CFS-CEC), in Monteverde, Costa Rica. This garden will be used for food production, but will also be used for educational purposes. Permaculture gardens teach students how to live with nature. They are able to produce food for themselves in a way that uses the least amount of land as possible, thus leaving this land for forest species. The garden provides various teaching tools such as native species, gap area, gardening techniques, mimicry complexes as well attracts various species. It will also provide crops for the school lunch program, so that students will receive a nutritional meal daily that they grew themselves. The garden also provides a place for students to simply go and enjoy nature. Enclosed is a layout for the garden, a budget for the project, as well as identification guide for the different species.

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  Physical defenses against herbivory in Gesneriaceae, June 2006

  Meagan Turner

  I studied physical plant defenses in seven species within the family Gesneriaceae: Alloplectus tetragonus, Besleria princeps, Besleria solanoides, Besleria triflora, Columnea glabra, Columnea microcalyx, and Monopyle maxonii. The species display varying levels of pubescence and leaf toughness. The purpose here is to determine if these physical traits deter herbivores and decrease the amount of herbivory. Data were collected on plants growing along the Senderos Principal and División behind the Estación Biológica, and the Sendero Nuboso in the Monteverde Cloud Forest Reserve, Costa Rica, from April 16 to May 8, 2006. Twenty individuals from each species were sampled and the percent herbivory and the leaf toughness were determined for each leaf. Leaf surface categories were distinguished based on the density of pubescence; glabrous (one species), medium pubescence (four species), and high pubescence (two species). Results showed that as pubescence increased, percent herbivory increased, and as pubescence increased, leaf toughness also increased. Results also showed a significant difference across and between species in regards to percent herbivory and leaf toughness, with C. glabra being the toughest and B. princeps the most pubescent. There was no significant relationship between leaf toughness and herbivory. The study demonstrated that pubescence is not an effective defense against herbivory for the family Gesneriaceae. Furthermore, toughness is not related to percent herbivory, thus suggesting there may be other factors involved such as palatability or secondary compounds that deter herbivores from the less tough leaves. Lastly, differences among species in these defensive traits further illustrate the trade-offs that plants perform in order to maximize their efficiency.

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  Pyrrolizidine alkaloids in néctar: Deterrents to generalist pollinators and nectar robbers, June 2006

  Arden G. Piland

  Pyrrolizidine alkaloids (PAs) are toxic chemicals found in multiple plant families. Eight experiments were conducted in Gardens 2 and 3 of the Monteverde Butterfly Garden to examine if PAs function as deterrents to generalist Heliconiine (Nymphalidae: Heliconiinae) butterflies and ant nectar thieves. To examine if Heliconiine butterflies were deterred by PAs in nectar, cut and naturally growing flowers were manipulated to contain either a 20% sucrose solution, a solution containing 20% sucrose and PAs, a solution made with 20% sucrose and plant material that did not contain PAs, or were flushed with water to produce an “empty” effect. Heliconiine visits to flowers with PAs were significantly different from only sucrose. Visits to flowers containing the PA solution significantly decreased in frequency and duration while visits to other groups of flowers generally increased in frequency and duration. This suggests that PAs act to deter generalist butterflies. To test if PAs also deter ant nectar thieves, four different nectar solutions (one with 20% sucrose solution and PAs, one made from a species closely related to the flower used to extract the PAs and 20% sucrose, one made from Lantana sp. flower heads and 20% sucrose, and one 20% sucrose solution) were offered to ants on small pieces of plastic placed randomly around the garden. After twenty minutes the plots were surveyed and the number of ants and type of ant found on each of the four solutions were recorded for each plot. Three different species of ant visited the plots but only one species was found per plot. For all three species of ant, the solution containing PAs was the least visited. This suggests that pyrrolizidine alkaloids also act to deter potential ant nectar robbers.

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  Rar especies advantage against herbivory among epiphyte Peperomia spp. (Piperaceae), June 2006

  Nichole Tiernan

  Herbivory is often a greater problem for tropical plants than for temperate plants. With higher herbivore pressures, tropical plants have more defense mechanisms than temperate plants. This drives host specialization and helps to explain why the tropics are so diverse. One premise that attempts to explain how the tropics can be so diverse is the rare species advantage. Two theories that help to explain the rare species advantage are those of density dependence and frequency dependence. The purpose of this study is to see if there is density or frequency dependent herbivory in species of the epiphytic genus Peperomia. By looking at herbivory rates of Peperomia in Monteverde, Costa Rica, this study has deduced that mean percent abundance is positively correlated with percent herbivory (p = 0.008) and thus suggests that density-dependency is an active theory in tropical forests. Frequency dependence however was nonsignificant when correlated with mean percent herbivory (p = 0.181). The rare species advantage has important implications for the maintenance of biodiversity as it drives speciation and helps keep host plants genetically and morphologically varied. Density dependence offers an explanation as to why Peperomia is such a species diverse genus in Monteverde.

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  Reproductive decisions of pollinator (Agaonidae) and non-pollinator (Torymidae) fig wasps of Ficus pertusa (Moraceae), June 2006

  Kevin J. Loope

  Ficus pertusa (Moraceae), a common Neotropical fig, is host to one pollinating (Agaonidae) and three nonpollinating (Torymidae) fig wasps. Bronstein (1991) addressed interspecies interactions between these species and suggested they may be partitioning resources within individual fig inflorescences (syconia) due to a forced association and observed morphological differences. I tested whether or not these wasps’ partition oviposition sites within a fig based upon distance from the syconium wall. Also, these wasps exhibit different reproductive strategies that vary the degree of local mate competition (LMC) between brothers for mates. LMC and inbreeding have been used to explain female-biased sex ratios (Harre 1985; Frank 1985) and this system provides an excellent opportunity for comparison between different reproductive strategies. I censured 30 syconia to determine distribution of different species within the syconia and the sex ratios of each species. I found that the wasps do not partition florets based upon height (ANOVA, F = 0.148, p > 0.05, df= 3). However, the presence of many (16 out of 30) unpollinated but torymid-infested syconia call into question the assertion that torymids rely on the pollinator wasps, as suggested by Bronstein (1991). In addition, I found that while LMC/inbreeding may impact the sex ratios of two wasps, Pegoscapus silvestrii (Agaonidae) and Idarnes sp. (Torymidae), another mechanism is needed to explain the high sex ratios, 0.5 and 0.6, found in the torymids Species 3 and Aepocerus respectively. I suggest several potential explanations: a high cost for female production, local resource competition (LRC) among related females or an equilibrium established between natal-fig mating and dispersing males.

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  Seed preference in the central american agouti, Dasyprocta punctata, June 2006

  Kristen Coogan

  Scatter-hoarding animals in the tropics typically depend on a cached supply of reserves when food is scarce. The Optimal Foraging Theory seeks to explain the behaviors these organisms exhibit upon prey selection. It is important for these scatter-hoarding animals to choose the most beneficial food item that will increase their energy intake. Central American agouties (Dasyprocta puncata) were presented with two differently sized seed species, the water apple (Syzygium malaccense) and the peach palm (Bactris gasipaes). A total of 400 flagged seeds were used, 200 of each species in groups of 20 seeds per species, over a 14 day period in Monteverde, Costa Rica. The seeds were collected and observed to determine seed fate. There was a significant difference in seed weight between the two species (T-test, p = <0.0001) and a significant difference between which species D. punctata chose to cache more ((2, p = <0.05), although there was no significant difference between which seed species D. punctata chose to eat (2, p=>0.05). Although D. punctata chose to cache more of the larger seed species, size and weight alone may not be the only measure for seed selection, therefore D. punctata may exhibit other selection processes in order to obtain its energy intake.

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  Sequestration and release of nutrients from mist by epiphytic mosses and orchids, June 2006

  Lauren Bennett

  Epiphytes sequester required nutrients and moisture from mist; the remaining moisture is then released as throughfall for other organisms. I proposed that there were differences between types of cloud forest epiphytes in the amounts of nutrients that they sequester. Using mist collectors filled with three different types of epiphytes (mosses, orchids without pseudobulbs Pleurothallis ruscifolia, and orchids with pseudobulbs Encyclia pseudopygmaea) and a control (empty) mist collector, I compared concentration of mist that passed through the control collector and three epiphyte groups throughfall of volume, nitrate concentration, phosphate concentration and pH level. I found no significant difference in the volume, nitrate concentration or pH levels in the throughfall of epiphyte groups (Kruskal-Wallis, H = 3.16, P = 0.37; H = 1.46, P = 0.69; H = 7.49, P = 0.06 respectively). There was a significant difference among the phosphate concentration of the mist and P. ruscifolia (Kruskal-Wallis, H = 6.56, P = 0.04 and Tukey’s test, Q = 2.43, P = <0.05), indicating these orchids leach phosphate. The concentration of nitrate was positively related to the volume of water collected (simple regression, R2 = 0.57, P = 0.04). There are many possible unstudied atmospheric conditions could account for this relationship. The concentration of nitrate was significantly greater immediately following a drought in comparison to days with normal precipitation (one-sample t- test, t = -14.67, P < 0.01, hypothesized mean = 1.36 ppm), following the known trend that atmospheric ion concentrations are greater at the end of the dry season, and are found in high concentrations following normal rainfall. Using a second study site I collected mist to determine if there were differences in mist precipitation with altitude. There were two days that did not have matching mist precipitation between the two study sites, indicating a possible altitudinal difference.

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  Stomatal density and aperture in four species of pleurothallid orchids (Orchidaceae), June 2006

  Kristen Becklund

  This experiment explored stomata density and aperture in four different species of epiphytic orchids in the sub-tribe Pleurothallidinae. Pleurothallids are likely to exhibit stomatal adaptations that reduce transpirational water loss because they are subject to the xeric conditions of the canopy environment and lack water-storing pseudobulbs. I calculated daytime and nighttime frequencies of open stomata on leaves of Masdevallia chasei, M. striatella, Lepanthes monteverdensis, and L. ciliisepala in order to test their ability to respond to environmental fluctuations in the short term. In order to see if pleurothallids can respond adaptively to water stress over longer time scales, I calculated stomatal densities on young and old leaves of each species to test for an effect of seasonality. L. ciliisepala and L. monteverdensis showed significantly higher daytime and nighttime frequencies of open stomata than M. chasei and M. striatella (1- way ANOVA, F = 12.23, p < 0.01 and F = 4.84, p < 0.01, respectively). Leaves from the two species of Masdevallia showed higher frequencies of open stomata at night than during the day, suggesting the potential for Crassulacean Acid Metabolism (CAM) in these species. Masdevallia striatella had significantly higher densities of stomata on young leaves as compared to old leaves, which may be a result of a peak in plant growth during the dry season (1-way ANOVA, F = 5.25, p < 0.01). Understanding the environmental cues that influence stomata density, opening, and closure and identifying how waterconserving stomatal adaptations vary between species will allow scientists to make predictions about how different epiphytic orchids will fare in the face of human-induced climate change.

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  Streambed substrate composition and macroinvertebrate communities in the presence of a dam, June 2006

  Julia Goldstein

  The construction of dams to satiate human year-round water needs has been so extensive in the past 50 years that small streams are some of the world’s only water flows to still run unregulated (Allan, 1995; Vitousek et al., 1997). That said, plenty of small stream water regimes are regulated, and the effects of this on biodiversity are under-investigated, especially in the tropics (Allan, 1995). In this study the effects of a small dam on the physical environment and macroinvertebrate communities of a tropical montane stream, the Quebrada Máquina, in Monteverde, Costa Rica, were analyzed. Substrate composition, temperature and macroinvertebrate diversity were measured between April 8 and May 4, 2006. I collected1592 macroinvertebrates and identified them to family and morphospecies level, over two-thirds of these individuals coming from the order Diptera. On a biological level, the numbers of orders and morphospecies decreased significantly as distance to the dam decreased. Physically, temperature increased significantly between 50 m upstream of the dam and 50 m downstream. Relative percentage of sand as substrate (RPSS) decreased significantly as distance from the dam decreased, and sediment as a substrate increased significantly at sites closer to the dam. While some of this study’s conclusions are unique to the Quebrada Máquina, many of its findings are universal to stream-dam situations. Taking what can be generalized from this experiment, I propose conservation strategies relevant to all dammed aquatic ecosystems.

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  Testing the unified neutral theory using the epiphylls of Geonoma spp. (Arecaceae) as model communities, June 2006

  Caroline Farrior

  This experiment tests the predictions of the Unified Neutral Theory of Ecology (Hubbell 2001) using epiphylls on leaves of the palm tree Geonoma spp. Arecaceae) as local communities. The metacommunity is defined as the collection of leaves of one palm tree. The UNT assumes all species to be competitively equivalent and population sizes to remain constant overtime. It also asserts that community drift is strong and that for diversity to exist there must be factors that slow its progress. The UNT predicts that increases in connectivity of the metacommunity, community area, population size of local and metacommunities, as well as metacommunity area should slow the rate of community drift and favor increased species richness. The UNT also predicts that Dominance-Diversity relationships of each metacommunity will form a family of curves that will differ in slope in relation to differences in community richness, rates of immigration between communities, and community sizes. Data taken on the epiphyll richness of different Geonoma spp. leaves support predictions that community and metacommunity size are positively correlated with species richness. The data shows no evidence of the effects of connectivity or population size on species richness. The model communities provided Dominance-Diversity curves of which the slopes were negatively correlated with species richness, but community size had no significant effect. I found Hubbell’s Unified Neutral Theory to be an insufficient model of epiphyll community richness and dominance on Geonoma spp. leaves in the cloud forest of Monteverde, Costa Rica.

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  Use of pheromones to enhance foraging efficiency in Atta cephalotes, June 2006

  Rachel Schiesher

  Atta (Formicidae: Myrmicinae) are important herbivores in the Neotropics, cutting between 12 and 17% of the vegetation there (Holldobler and Wilson 1990). Atta cephalotes uses pheromones to communicate and maximize efficiency during foraging. The presence and specificity of pheromones was studied on leaf segments, between trails in the same colony and between different colonies. All studies were completed at the Santuario Ecológico in Cerro Plano, Costa Rica. Leaves cut by ants were retrieved from the cache at a significantly faster rate than those cut by hand (p-value = <0.0001), suggesting pheromones were laid on the plant material. The leaves were also retrieved at a significantly faster rate when compared to leaves collected from ants on a different trail within the colony or from a different colony (p-value = 0.0386 and 0.0010 respectively). Individual ants also foraged at a significantly faster rate on their own trail when compared to when they were transferred to a different trail within the colony or to a trail of a different colony (both p-values = <0.0001). This suggests that the trail pheromones used for foraging are more complex and specifically recognized by workers on a certain trail. A higher specificity of pheromones may prove beneficial to the enhancement of worker specialization and colony foraging efficiency.

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  A lesson plan on fungi diversity for the Centro de Educación Creativa, November 2005

  Rachel Deliz

  Fungi are integral components of a forest environment, but they are often overlooked in elementary education, despite their crucial role in nutrient cycles. Concepts pertaining to fungi diversity were researched and compiled to be part of the 5th grade curriculum of Centro de Educación Creativa. The result of this project was three PowerPoint presentations, each coupled with 2-3 visual aids, experiments and/or activities. I expect these presentations to aid in the environmental education curriculum at the C.E.C and to promote an appreciation of the Kingdom Fungi.

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  Community composition and diversity of lichens along a disturbance gradient in San Luis, Costa Rica, November 2005

  Sarah Hosford

  This research was conducted to better understand lichen morphology and diversity in different habitats in San Luis, Costa Rica. Lichens on trees in adjacent pasture, forest edge, and mature forest areas were identified to morphospecies and the species richness, diversity and total coverage per tree was compared across habitats. Eighteen different morphospecies were found across all three habitats. The forest trees had the lowest species richness and diversity, while the forest edge and the pasture had the highest.

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  Community composition Coleopteran’s at two different elevational ranges, November 2005

  Carrington Dahmer

  The order Coleoptera is the most diverse among animals, composing 70-80% of all described animals in the world. (White 1983) Even though this order is the most described in the world, there is still very little known about their composition in the canopy. Diversity and abundance of the canopy was investigated along elevational ranges attempting to find whether the increase in elevation played a factor in the Coleopteran composition within the canopy. Beetles were sampled at two different elevations in the Monteverde cloud forest at La Estación Biológica, Monteverde, Costa Rica. Diversity was found to be highest at the low elevation and the high elevation exhibited a higher abundance. These data suggest that diversity may closely follow a pattern stating that increases of the elevation produce decreases in diversity. Abundance has been found to follow this pattern also, but not as closely, leading to abundance functioning independently of this pattern.

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  Database of the macrofungi of the Monteverde Reserve, November 2005

  Corey Rogers

  Fungi serve important roles in natural systems and have strong economic and social consequences for human populations. A database of the macrofungi of the Monteverde Reserve was created to ease identification and facilitate research on local macrofungi. The database includes 30 species, with 18 families and 22 genera represented. The database was organized in a system of nested folders, providing both morphological and taxonomic keys. Information files were created for each species, including digital photographs of specimens and spore prints (when applicable), and taxonomic, microhabitat, growth, and morphological data. This database provides a structure for future cataloguing and identification, with the goal of spurring fungal research in the area.

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  Distributions of epiphytic orchids and bromeliads on secondary forest and pasture trees, November 2005

  Greta Brom-Palkowski

  The locations and densities of epiphytic orchids and bromeliads growing on host trees are influenced greatly by differences in epiphyte requirements for light, moisture and nutrients. Because these factors differ greatly between minimally and highly disturbed habitats, epiphytic composition may also be altered. This study examined changes in epiphytic orchid and bromeliad density between hosts in secondary forest and pasture. Fifteen trees in each habitat type were censused for the abundance of orchids and bromeliads in different parts of the trees. Results indicated that the highest concentration of both orchids and bromeliads is in the pasture. In addition, in both forest and pastureland, the highest density of epiphytes was recorded in tree regions characterized by secondary to tertiary branching. Significant results were also obtained which highlighted a positive correlation between orchids and bromeliads in both habitat types. Overall, results indicate that land conversion for human use has a great impact on the quantity and location of epiphytic orchids and bromeliads living on remnant trees.

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  Effect of herbivory on succession of forest light gaps, November 2005

  Toby Jacobs

  Effects of herbivory have been seen to vary according to the particular growth form of a plant and its habitat. The idea that these factors can interact to determine the nature of gap succession has been suggested but has not yet been thoroughly explored. Leaves of pioneer, understory, and canopy plants were collected and analyzed to quantify herbivory levels on each growth form. Herbivory was found to be higher in gaps (p = 0.0015), and this was true to varying degrees with respect to growth forms and single families. Results suggest that herbivory is not the main factor influencing instantaneous or eventual gap composition, but it could interact with other effects like competition for light and water. The study also does not rule out the possibility that gap composition is random.

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  Effects of trail traffic on egg-predation by mammal populations in the Monteverde Cloud Forest Preserve, November 2005

  Karmen Scott

  The effects of human traffic within trails on egg predation and predatory mammal compositions between heavily trafficked trails and secluded trails were studied at the Monteverde Cloud Forest Preserve. This study was able to find differences in egg-predatory mammal compositions between these two trail types by looking at teeth impressions in eggs made of plasticine. The main predator was found to be Nasura narica (common coati) who was involved in the majority of the egg predation events and the vast majority of the nests preyed upon were on the highly trafficked trail. There were only a few predation events from other mammals such as rodents and Cebus capucinus (white-faced monkey). In this case, the abundance of tourists have altered populations of a mesopredator, Nasua narica by providing a new food source for them (garbage and tourist’s lunches) and by affecting the rarity of their predators (boas, cats and Tayras) whom steer-clear of human populated areas and therefore steer-clear of N. narica. This dualistic relationship acting on the population of N. narica makes for an increase in the carrying capacity and, hence, further predation. This imbalanced egg-predation by N. narica on tourist trails allocates the disruption of their prey populations. Studies of the impacts of tourism have important conservation implications because tourism can have a tremendous disturbance on structure and community function.

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  Effects of weather conditions on pollinator behavior at Stachytarpheta jamaicensis (Verbenaceae), November 2005

  Michelle Murguia Tamez

  Competition between pollinators, such as nectar-eating birds, bats, and small insects, plays an important role in understanding resource distribution among feeding guilds (Murray et al. 2000). This study suggested that territorial behaviors exhibited by hummingbirds are not hardwired, but rather, they may be affected by abiotic factors such as weather conditions. An individual may increase its energy budget through selective defense of a plant. Hummingbird and butterfly visits to and agonistic interactions (i.e. chases) at a Stachytarpheta jamaicensis plant were observed for a total of 40 hours and weather conditions were quantified. As the activity of butterflies (a competing species) increased in good weather, hummingbird defense of a plant decreased for species known to be territorial. Conversely, during adverse weather conditions, butterfly activity was depressed and energy used for defense of a plant was beneficial for hummingbirds. Observations showed that species typically known for traplining also displayed territorial behavior during these conditions. Multiple regression analyses showed that hummingbird visitation increased significantly as wind speed increased (R2 = 0.11, F = 0.05, p < 0.037, N= 668). Butterfly visitation increased significantly with an increase in light intensity (R2 = 0.55, F = 0.0001, p < 0.012, N= 926) and decreased with increased cloud cover (R2 = 0.55, F = 0.0001, p < 0.004, N= 926) and index of rainfall (R2 = 0.55, F = 0.0001, p < 0.008, N= 926). One-way ANOVAs showed that there were significant differences between the number of interactions and all weather parameters (temperature F = 76.14, p < 0.0001, df = 152; light F = 29.57, p < 0.0001, df = 123; wind F = 9.66, p < 0.0001, df = 123; cloud F = 24.00, p < 0.0001, df = 123; rain F = 13.44, p < 0.0001, df = 123).

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  Endosperm loss, seed germination, and early seedling growth in large-seeded tropical trees, November 2005

  Audrey L. Quinn

  Endosperm damage was studied in Monteverde, Costa Rica to determine its frequency, extent, and effect on seed germination and early seedling growth. Endosperm damage was found to occur in 72% of seeds from Chione sylvicola (Rubiaceae) and 94% of seeds from Quercus costaricensis (Fagaceae). The extent of endosperm damage in Q. costaricensis was not related to the root and shoot weight of germinated seeds. Experimental endosperm removal was carried out in Persea americana and Cinnamomum paratriplinerve (both Lauraceae) seeds. The three week time period of the study was inadequate to yield significant C. paratriplinerve germination, but seeds with intact endosperm were much less likely to suffer fungal infection. Endosperm removal did not inhibit germination in P. americana seeds, even when 80% of the original seed weight had been removed. After 23 days in soil, most seeds were just beginning to produce roots and shoots, the majority of which were still enclosed in endosperm. At this time, P. americana seeds with a higher percent of endosperm removed had significantly heavier roots and shoots, suggesting a reduced or even inhibitory role of endosperm in initial seed germination.

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  Extra extrafloral nectaries and anti-herbivory protection in Inga sierrae (Fabaceae: Mimosaceae), November 2005

  Camryn Pennington

  Extrafloral nectaries (EFNs) in plants are known to attract insects such as ants and wasps that drink nectar and in turn protect the plant from herbivores (Bentley 1977). In this study, ten year old Inga sierrae (Fabaceae: Mimosaceae) trees planted on a fallow pasture at 1535 m in Monteverde, Costa Rica have been observed to have extra EFNs on their leaflets in addition to the normal three located on the rachis between the leaflet pairs. The leaves of 20 trees were sampled to determine the local distribution of EFN number. Percent herbivory was determined for leaves with a varying number of EFNs by dividing damaged leaf surface area by total leaf surface area. In addition, insects were captured on leaves for eight days to find out if more protective insects visit leaves with more EFNs. The number of simulated insects eggs (made of animal lard) removed from leaves over 24 hours was used as a proxy for the level of predatory wasp activity on leaves with varying numbers of EFNs. Thirteen of 20 sampled trees had some leaves with extra EFNs. The number of extra EFNs ranged from one to five, and a linear regression revealed a significant trend between a higher numbers of extrafloral nectaries and lower herbivory on a per leaf basis (r2 = 0.0236, p = 0.0461, n = 169). No trends between the number of EFNs and either the number of protective insects captured on leaves or the number of simulated herbivore eggs removed by predatory wasps were observed, however more parasitoid than predatory wasps were captured. These results show parasitoid wasps are the primary I. sierrae EFN visitors and suggest higher numbers of EFNs confer higher fitness to leaves. Trees with extra EFNs should produce more offspring and, hence, extra EFNs will become more prevalent in the I. sierrae population.

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  Increased agonistic behavior in hummingbirds (Family Trochilidae) in Monteverde, Costa Rica with a reduction of food at artificial feeders, November 2005

  Taegan A. McMahon

  This study looked at the change in agonistic behaviors of hummingbirds (Family Trochilidae) with the reduction of an established food source at la Estación Biológica de Monteverde (1567m elevation), Costa Rica. There were three treatment periods: three feeders (ten days), one feeder (six days; reduction of food source), and three feeders (four days) between October 23 and November 14, 2005. The agonistic behaviors were the number of agonistic behaviors recorded, as well as the species composition of aggressors versus recipients. Over the three treatment periods there was an increase in hummingbird visits (treatment one to treatment two: p = 0.0030; treatment one to treatment three: p = 0.0005), agonistic behavior when the food source was reduced (p = 0.0148), and tolerance when the food source was replenished (p = 0.0412). The four dominant aggressors were: Lampornis calolaem, purple throated mountain gem, Eupherusa eximia, striped tailed hummingbird, Colibri thalassinus, green violet ear and Campylopterus hemileucurus, violet sabrewing; the three most targeted recipients were: E. eximia, C. thalassinus and C. hemileucurus. The artificial feeders increased agonistic behavior such as guarding and darting. This increase potentially occurred because it was more advantageous for the birds to guard the feeders, a constant, rich food source, than to trapline. Such behavior may cause an increase in territoriality and an alteration of the pollination system in areas with established artificial feeder gardens.

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  Mycorrhizal fungi in aerial and terrestrial roots of an epiphytic and two terrestrial species of Orchidaceae, November 2005

  Derren A.R. Eaton

  Very little is known about the mycorrhizal relationships of Costa Rican orchids, and even less is known about differences in the presence of mycorrhizae between aerial and substrate roots. All orchids require mycorrhizal symbionts during their germination stage, but few studies have examined mycorrhizal relationships in adult orchids. Aerial and substrate roots from three closely related species of Orchidaceae (two terrestrial and one epiphytic) were collected and examined for the presence of mycorrhizal fungi. Mycorrhizal fungi were found in 45 of 51 individuals. The epiphytic species exhibited a much lower occurrence of mycorrhizae in its aerial roots than the two terrestrial species did. This may be attributed to the effects of nutrient limitations of the different habitats. The terrestrial species showed a much more variable occurrence of mycorrhizae in both their aerial and substrate roots. This may be a result of a changing frequency of infection of mycorrhizae at different growth stages of the orchid, which result from different nutrient availability and the costs imposed on the orchids by the mycorrhizae.