DISSERTATION RESEARCH: Non-lethal Effects of Chytridiomycosis on the Reproductive Behavior of Tungara Frogs

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The world is experiencing the greatest vertebrate extinction in human history, because a fungus is responsible for the demise of many amphibian species. Currently, 168 amphibian species are extinct, and the number is rising. This study will investigate the effect of this emergent fungal pathogen on a tropical frog species. Although the pathogen is rapidly spreading and its infections are usually lethal, some species, including the focus of this study, appear to be resistant. The researchers will determine the sub-lethal effects of the pathogen on adults, tadpole survivorship, and female mate choice. This study will advance our knowledge of emergent diseases in the wild by showing the toll that such diseases take even on "resistant" species.This study will determine how chytridiomycosis, an emergent infectious disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), influences the reproductive behavior of frogs. Little attention has been given to sub-lethal effects of chytridiomycosis in resistant species. Túngara frog populations infected with Bd lack any clear signs of the disease, allowing us to examine how the potential pathogen-stress influences reproductive behavior. The first aim is to understand the basic epidemiology of chytrid infections in the widespread tropical Túngara frog. Since 2010, the researchers have sampled annually for the presence of Bd in populations of Túngara frogs from western Panama to the Darien Gap, an approximately 1000 km transect. All populations surveyed are currently infected with Bd. The second aim is to examine how the potential pathogen-stress induced by Bd interact with sexual communication, mate choice, vigor, and reproductive success. To assess if there is a trade-off between the response to the infection and calling behavior, the researchers will analyze males' advertisement calls before and after experimental infection with Bd. The researchers will perform female phonotaxis experiments with these same calls to determine if male infection with Bd influences female mate choice, and determine if there is a cost of the response to the infection in development and overall performance. Videos of behavioral tests, protocol details and data will be available to other researchers upon request, and will be publicly available after publication of results. Data back-ups will be securely stored in UT Box, at the Ryan Lab account in the TACC computer, and in external hard drives. As data are published they will be deposited in the DRYAD repository.