Dissertation Research: Genetic and Environmental Mechanisms Mediating Disease Resistance and Tolerance in Amphibians

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Identifying the causes of recurrent outbreaks of infectious diseases in the wild is critical to understanding human and ecosystem health. Environmental change may reduce the ability of hosts to evolve resistance or persist within their tolerance limits, thus making pathogens more likely to cause disease and mortality. This project investigates seasonally variable patterns of infection in tropical amphibians and tests the hypotheses that disease patterns are a consequence of changes in the frequency of individuals that have genetically-based resistance to the pathogen, or alternatively, a result of a weakened host condition caused by environmental stress. Frogs lacking genetic determinants may also rely on environmental modulators (e.g., symbiotic bacteria) to alleviate pathogen damage. How and when these immune strategies interact to allow amphibians to persist emergent diseases is unknown. Using declining frog populations in Puerto Rico that exhibit high heterogeneity and seasonality in infection dynamics, the PIs combine population genomics and metagenomics to determine how environmental and host adaptive responses affect the outcome of disease. The topic of amphibian declines, and its implications for environmental health, has reached public awareness; thus this project offers an excellent opportunity to educate non-scientists about genetics, immunity, and disease ecology. Both PIs disseminate their scientific findings to general audiences through media, educational outreach, and NGOs. In addition, the project involves students and researchers from underrepresented minorities, fosters collaborations between USA and Puerto Rican institutions, and increases diversity among students interested in ecology, evolution, and conservation. These results can be used by conservation agencies in species prioritization schemes and captive breeding programs.