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  • Undergraduate Poster Abstracts
  • Ecology/Evolution

    Room Annapolis 1-2

    ap017 POPULATION STRUCTURE IN CARICA PAPAYA IN PANAMA

    • Sandra Mardonovich ;
    • Richard Moore ;

    n/a

    POPULATION STRUCTURE IN CARICA PAPAYA IN PANAMA

    Sandra Mardonovich, Richard Moore.

    Miami University, Oxford, OH.

    The biodiversity of wild relatives of crop species can be threatened by genetic introgression of cultivated traits from co-occurring cultivated varieties or feral escapees. The tropical fruit crop papaya (Carica papaya L.) originated in Mesoamerica, where today it is both cultivated and found in disturbed natural areas where it acts as a pioneer species. Thus, papaya serves as a model to study the effects of gene flow among cultivars and natural populations of their wild relatives. Naturally occurring papaya found near the purported center of domestication in northern Mesoamerica have rounded fruit similar in size to a tennis ball. In contrast, fruit found further south resemble the larger-fruited cultivated papaya, suggesting there has been introgression of cultivated crop traits into wild populations. Small-fruited papaya, though, have been reported as far south as Costa Rica, questioning this prediction. To further question this prediction, we sampled the morphology and genetic diversity of natural papaya populations in Panama, which extends beyond papaya’s hypothesized center of origin. Forty-two individuals were analyzed for qualitative and quantitative morphological traits in 4 regional populations in Panama. The levels and patterns of genetic diversity were measured using 20 molecular markers in 82 samples and compared to the diversity of 14 exotic cultivars to look for signs of genetic introgression from cultivars. STRUCTURE was implemented to determine cryptic population structure, and 2 of the 4 regional populations share genetic similarities with the cultivars. This data provides more insight into the domestication history of this important fruit crop.

    ap018 POPULATION COMPOSITION OF AN EXPLOITED HAWAIIAN FISHERY

    • Patricia Cockett ;
    • Christopher Bird ;

    n/a

    POPULATION COMPOSITION OF AN EXPLOITED HAWAIIAN FISHERY

    Patricia Cockett, Christopher Bird.

    Texas A&M University-Corpus Christi, Corpus Christi, TX.

    Overharvesting has been implicated in altering the population structure of marine organisms, reducing genetic diversity and adaptive capacity. Overharvested fisheries can be particularly vulnerable to environmental and anthropogenic stressors due to the loss of advantageous mutations. The Hawaiian broadcast-spawning limpet Cellana exarata is subject to varying levels of harvesting pressure on different islands, ranging from no harvest on the uninhabited island of Nihoa in the Papahānaumokuākea Marine National Monument (PMNM), to a reduction in population density on Maui and Kaua‘i, to near extirpation on O‘ahu, the most populous of the Hawaiian Islands. In this study, we used genome-wide surveys of genetic variation (ezRAD, > 21,000 loci) on C. exarata from the islands of Nihoa, Kaua‘i, Maui, O‘ahu, and Hawai‘i to test for relationships between genetic diversity, population size, island age, and harvest pressure. Global estimates of genetic differentiation among islands were greater than those estimated with mtDNA. Estimates of nucleotide diversity (π) were greatest on Nihoa (π = 2.05 × 10−3), despite having the smallest estimated population size (without harvesting); estimates of nucleotide diversity on the Big Island of Hawai’i are the lowest of all the islands in this study (π = 1.71 × 10−3), despite having the largest estimated population size. This difference in genetic diversity is correlated with island age and indicates that C. exarata populations within the Main Hawaiian Islands (MHI) experienced a recent bottleneck. Overall, these results suggest that the PMNM harbors a stockpile of genetic diversity for C. exarata, despite relatively small population sizes when compared to the MHI.

    ap019 VARIATION IN VENOM GENE REPERTOIRES OF POPULATIONS OF 3 CONUS SPECIES

    • Peter Cerda ;
    • Thomas Duda ;

    n/a

    VARIATION IN VENOM GENE REPERTOIRES OF POPULATIONS OF 3 CONUS SPECIES

    Peter Cerda, Thomas Duda.

    University of Michigan, Ann Arbor, MI.

    Understanding the impacts of species interactions on organismal evolution is a key aim in biology. Because venoms act directly at the interface of species interactions (i.e., prey capture and/or defense) and contain direct gene products, it is possible to directly evaluate the role of molecular genetic processes related to an organism’s ecology. Cone snails (family Conidae) are a diverse group (>700 species) of predatory marine gastropods that utilize venom to capture prey. Venom composition varies tremendously among and within species. Venom components (conotoxins) are expressed by members of many gene superfamilies and subject to strong positive selection. Conotoxin gene families also show high levels of gene turnover (i.e., high rates of gene duplication and gene loss) that effectively restructure gene family composition among species. Nonetheless, while all previous studies of venom gene family composition have focused on patterns of variation among species, no work has yet addressed the effects of high rates of gene turnover on patterns of variation within species. Here, we evaluated the composition of A-superfamily conotoxins of individuals of several populations of 3 Conus species. In particular, we designed locus-specific primers for multiple A-superfamily conotoxin genes and used amplifications with these primers to determine the presence/absence of these loci in individuals. We quantified and compared levels of variation in gene family composition within and among populations of the 3 species. Results will indicate the importance of gene turnover in generating and maintaining diversity of venom genes within species.

    ap020 PHENOTYPIC COVARIATION OF CARAPACE MORPHOLOGY AND NESTING BEHAVIOR IN THE PAINTED TURTLE

    • Daniela Flores ;
    • Jaymie Reneker ;
    • Daniel Warner ;
    • Fredric Janzen ;

    n/a

    PHENOTYPIC COVARIATION OF CARAPACE MORPHOLOGY AND NESTING BEHAVIOR IN THE PAINTED TURTLE

    Daniela Flores1, Jaymie Reneker2, Daniel Warner3, Fredric Janzen1.

    1Iowa State University, Ames, IA, 2University of North Carolina Wilmington, Wilmington, NC, 3The University of Alabama at Birmingham, Birmingham, AL.

    Parental care varies across vertebrate taxa, ranging vastly from high-input care in mammals to very limited care in some reptiles. In some oviparous species, such as the painted turtle (Chrysemys picta), parental care is limited solely to maternal effects in terms of egg size, yolk hormones, and nest microenvironment. Maternal nest-site choice is especially critical in species like C. picta that have temperature-dependent sex determination, in which incubation temperatures permanently dictates the sex of the offspring. This project combined field and laboratory studies to examine morphological indicators of a female’s nesting behavior and clutch sex ratio in C. picta. Nesting females in the field were characterized as flat, domed, or intermediate based on carapace measurements. Vegetation coverage of each nest site was quantified, and sex ratios were obtained after egg incubation either in the field in their natural nests or in the lab at a temperature to produce both sexes. Carapace morphology was associated with nest-site choice, with more domed females nesting in shadier sites and flatter females nesting in sites with more direct sunlight. Carapace morphology and clutch sex ratio were associated only when eggs were incubated in their natural nests. This result was not mirrored in the lab experiment, implying that the primary influence on clutch sex ratio is a nest’s vegetation coverage. These results highlight a unique example of a morphology-behavior relationship in vertebrates that may influence population structure and fitness.

    ap021 INFLUENCES OF YARD MANAGEMENT INTENSITY ON URBAN SOIL BIOGEOCHEMISTRY

    • Viviana Penuela Useche ;
    • David Lewis ;

    n/a

    INFLUENCES OF YARD MANAGEMENT INTENSITY ON URBAN SOIL BIOGEOCHEMISTRY

    Viviana Penuela Useche, David Lewis.

    University of South Florida, Tampa, FL.

    Irrigation with reclaimed water is an increasingly popular water conservation strategy, yet the high salinity and nutrient content of reclaimed water has the potential to negatively affect soil properties. At 40 households in urban, subtropical Tampa, Florida, we surveyed residents for their lawn management behaviors and quantified irrigation water and soil chemistry. We tested whether there are distinct lawn management systems characterized by systematic differences in reclaimed water use and irrigation and fertilization practices. We then investigated whether soil biogeochemistry responds to lawn management systems. Three management behaviors co-occurred, as households that used reclaimed water tended to fertilize and irrigate more frequently. Reclaimed water had significantly higher conductivity and phosphate content than potable water. Distinct, high-amendment and low-amendment lawn management systems are thus evident. Residential soils receiving the high-amendment strategy exhibited higher conductivity and microbial biomass than soils receiving a low-amendment strategy. These findings suggest that the high-amendment strategy increases the input of some nutrients to soil and acts as a nutrient resource for soil microorganisms. These results further suggest that hierarchical social interactions between municipalities and individual households should be incorporated into the emerging conceptual framework of ecological urbanization. Specifically, as municipalities make management alternatives (reclaimed water) available to households, they may introduce spatial ecological variability at the finer within-neighborhood scale. Residential lawn management affects regional water supplies both through water consumption and nutrient runoff, and these results could inform how reclaimed water is advertised as a conservation measure as well as a source of soil fertility.