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«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»

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1 A fundamental question in ecology is why species would limit themselves to the number of hosts they use. Limiting the number of hosts also limits the resources available to them. Several species of ants in the arboreal genus Azteca are only found in Cecropia trees. Cecropia is a Neotropical genus of pioneer tree that grows rapidly and colonizes disturbed habitats. Azteca ants frequently colonize their hollow trunks and protect the trees from herbivores and encroaching vegetation. Eleven species of Azteca specialize on Cecropia and are found nowhere else. At Las Cruces Biological Station, Costa Rica, the Cecropia-Azteca association seems to occur in a highly specialized, one-to-one relationship. Cecropia insignis is common in the forest and associates with Azteca xanthachroa, while Cecropia obtusifolia is common in the meadow and associates with Azteca alfari. However, it is uncertain whether host associations are linked to habitat preference or host preference. The focus of this research is to address this question by collecting Azteca species and Cecropia species in places the trees are not commonly found: C. insignis in the meadow and C. obtusifolia in the forest. If ants are sorting by habitat, then they should be found in the forest or meadow regardless of host plant availability. The results of this work will provide insights into the ecology and evolution of host choice in plant ants.




Sandy Gutierrez1, Tesla Monson2, Leslea Hlusko2.

University of California, Los Angeles, Los Angeles, CA, 2University of California, Berkeley, Berkeley, CA.

1 After the type specimen for Australopithecus africanus, the Taung child, was discovered in the Buxton Limeworks in 1924, the search for hominids was directed to Africa. From 1947 to 1948, Charles Camp from the University of California’s Museum of Paleontology led a series of cave and travertine excavations along the Transvaal and Cape Provinces of South Africa in search of hominids and collected a variety of specimens. More than 2,800 vertebrate fossils were collected from approximately 41 sites, including everything from dinosaurs of the Permo-Triassic to Homo sapiens from the Pleistocene. These specimens have not been thoroughly studied to date. Among the specimens collected are approximately 370 avian fossils pertaining to the Pleistocene. The specimens collected in the Black Earth Caves can be dated back to the Middle and Late Stone Ages based on faunal assemblage and humanmodified artifacts. Two decorated ostrich eggshell fragments have been associated with the Wilton Culture of the Late Stone Age. Pore morphology, pore density and distribution, and eggshell thickness of 111 pieces of fossilized struthionid eggshell were examined across 5 sites. Ostriches are useful bioindicators and reveal information about the environment of the site. The variation in ostrich eggshell morphology at the Black Earth Caves will be presented in the context of what is known about the evolution of South African environments. Implications for the evolution of Struthio sp. and other fauna will be discussed.




Ridhima Vemula, Nyeema Harris.

University of California, Berkeley, Berkeley, CA.

Over the past three decades, the amount of protected area around the world has quadrupled from 3.2% of the world’s land surface area to greater than 12.2%. Protected areas not only foster biological diversity but also exploitative interactions such as parasites on their hosts. Some of these parasites are vectors for zoonotic diseases that harm human populations. We evaluated Ghana’s largest protected area, Mole National Park. We collected ectoparasites from live-trapped small mammals to explore ectoparasite prevalence and composition inside and outside the park

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Benjamin Sanchez-Sedillo, Lee Taylor.

University of New Mexico, Albuquerque, NM.

Nongreen, mycoheterotrophic plants, unlike most plants that are autotrophic, obtain carbon energy through a symbiotic relationship formed with fungi. Some species of orchid are highly specialized in parasitizing particular species of fungi. These associations are known to be supported by surrounding green vegetation, which are capable of fixing carbon by photosynthesis. Roots of the green vegetation are colonized by mycorrhizal fungi that in turn are parasitized by the mycoheterotrophic orchid Corallorhiza. We investigated the mycorrhizal community which grows near two species of nonphotosynthetic orchids: Corallorhiza maculata and Corallorhiza wisteriana. A quantitative and morphological analysis of the mycorrhizal fungal community that grows adjacent to Corallorhiza in collected soil samples can inform us about the specificity Corallorhiza has toward its prey and the community context in which they grow. Ten samples of Corallorhiza were collected in the San Pedro Wilderness of New Mexico. Out of the 3,623 root tips collected, 16.70% of the 2,635 tips from 7 C. maculata samples belong to species of Russula; 17.81% of the 988 tips from 3 C. wisteriana samples belong to putative species of Tomentella, the genus targeted by this orchid. Molecular analyses of the 10 samples is still in process in order to determine the species of fungi, trees, and Corallorhiza genotypes sampled. The results to date suggest that in a small area where nearly 20 different species of fungi live, these two orchids target mycorrhizae that are more abundant than others.




Drew Talley1, Lindsay Goodwin2, Joel Urbina2.

University of San Diego, La Jolla, CA, 2Ocean Discovery Institute, San Diego, CA.

1 Seemingly distinct habitats are often deeply interconnected through the provision of food resources or nutrients across habitat boundaries. These connections, known as trophic spatial subsidies, can often be the dominant force structuring communities in these connected systems. This study examined the potential spatial subsidies between islands used by birds and the surrounding coastal waters. We used nutrient analysis of surface waters and GIS to map the spatial distribution of nutrients around islands with varying levels of bird use to better understand the potential for ornithogenic nutrients to link the terrestrial and aquatic ecosystems in Bahía de los Angeles, Baja California, Mexico. Preliminary results suggest islands exhibit a plume of nutrient enrichment extending from the heavily guanocovered islands, which may in part account for the relatively high abundance of phytoplankton and zooplankton in the waters of Bahía de los Angeles. Further study will focus on examining the phytoplankton and nekton communities in the bay, where we can use stable isotope analysis techniques in an effort to complete the chain of relationships between ornithogenic nutrients and large grazer populations in Bahía de los Angeles.



CRUCES, COSTA RICA Devan Tatemichi1, Andy Michelson2.

Kapiolani Community College, Honolulu, HI, 2University of Chicago, Chicago, IL.

1 Introduction of excess nutrients into aquatic environments, caused by fertilizer runoff from farmlands, can be detrimental to the point of creating dead zones. These dead zones are areas of low oxygen caused by the respiration of huge algal blooms. Tank bromeliads are great study systems that can simulate these stresses in microcosm. We


designed 2 complementary methods to understand the effects of eutrophication on arthropod communities in tank bromeliads (Guzamnia wittmackii) in southern Costa Rica. The first method used 15 natural bromeliads: 5 were used as a baseline for arthropod diversity living within them and 10 had 1 mL of 70% diluted organic fertilizer made at the Las Cruces Biological Station added every 4 days and were collected on days 7 and 14 to determine the progression of said communities. The other method uses 15 artificially simulated bromeliads filled with 25 mL of filtered bromeliad water and 25 mL of diluted rainwater. Five of these 15 were controls; the other 10 were fertilized with 1 ml of 70% diluted organic fertilizer added every 4 days and were harvested in the same manner as the previous method. The expected result is an increase in species richness as result of algal production and the arrival of primary consumers, which will attract a greater number of predator species. By adding these nutrients, algal production should increase but not so much that dead zones occur because of the appearance of primary consumers that limit the growth of algae populations in these tank bromeliads.



Tuong-Vy Nguyen1, Jennifer L. Burnaford2.

University of Washington, Seattle, WA, 2California State University, Fullerton, Fullerton, CA.

1 Intertidal, marine seaweeds experience different environmental conditions during high and low tides. Low tide conditions may be stressful for seaweeds because desiccation and extreme light levels may impact their ability to photosynthesize. We examined the effect of low tide exposure on the photosynthetic health of the canopy-forming seaweed Saccharina sessilis in the field and lab. Field studies assessed the health of marked individuals on days with varying environmental conditions, while lab studies separated the effects of those different conditions. We hypothesized that the seaweed’s photosynthetic health depended on weather. We predicted that health would decline over a single stressful low tide (high light, high wind, and high temperature), but not over a benign low tide (low light, low wind, and moderate temperature). We assessed health in multiple ways. First, we measured dark-adapted maximum quantum yield (MQY) via pulse-amplitude-modulated (PAM) fluorometry, which assesses the photosynthetic ability of photosystem II. Second, because we observed that the seaweed changes color following intense stress, we evaluated tissue damage by quantifying the proportion of blade area in 5 color categories. A single stressful low tide can reduce MQY readings to 5% of preexposure values and damage 61% of a blade’s area. Individuals in benign conditions had MQY values of 97% of preexposure values and only 1% of blade area damage. Over the long term, damage from low-tide exposure may limit growth and reproductive output. Understanding how individuals and populations respond to daily stresses will aid in understanding their responses over longer time scales.




Adolfo Gomez1, Vance Vredenburg2, Michelle Koo1.

University of California, Berkeley, Berkeley, CA, 2San Francisco State University, San Francisco, CA.

1 One third of amphibian species are at risk of extinction. A common, swift, and dramatic cause for their decline is the infectious fungal disease chytridiomycosis, which is caused by the aquatic fungal pathogen Batrachochytrium dendrobatidis (Bd). Although there are many studies documenting the disease and its spread across the globe, a comprehensive database of all species affected by Bd has yet to be compiled. This study aims at creating a GIScompatible database of species with known Bd infections, species Bd susceptibility status, and species ranges to allow us to determine which species have been extirpated and which are susceptible to Bd but do not develop chytridiomycosis (pathogen reservoir species). Carriers of Bd are believed to play a large role in the spread of Bd into naïve host populations, resulting in massive die offs. This study will also allow us to study patterns in taxonomy, biogeography, and natural history of those species that are susceptible to Bd infections. Such information can allow us to predict species that might be affected in the future, making the allocation of already limited conservation resources more efficient. This information will also be integrated into AmphibiaWeb, which is used by students and researchers worldwide.

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The narrow-leaved purple coneflower Echinacea angustifolia (Asteraceae) is the only native echinacea species found in Minnesota tallgrass prairies. Due to high levels of habitat fragmentation in this area, many restoration projects have been developed in these tallgrass prairies recently. Some of these restoration efforts have introduced non-native echinacea species (Echinacea pallida and Echinacea purpurea). These species could potentially have detrimental effects on the native echinacea species as well as on the arthropod communities that depend on this plant. A specific concern is the invasion by hybridization between native and non-native echinacea species. Last year we successfully tested the likelihood of hybridization between Echinacea pallida and Echinacea angustifolia using artificial crosses and demonstrated that each species accepts interspecific pollen and seedling results. Because we still do not have any evidence that such hybridization occurs in nature, we will identify and contrast the pollinator species that visit each echinacea species to determine the ultimate possibility of hybridization among these plant species. Simultaneously, we will study echinacea plants in the field to quantify synchrony in the time of flowering between the local and the introduced species. We will observe, record, and collect pollinators for later identification using high-resolution cameras and an existing reference pollinator collection. Because both species are visited by generalist pollinators, we hypothesize that the introduced species are very likely to hybridize and may displace the native species in nature. The information we gather from this research will indicate how important it is to use local flora in restoration projects.



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