Dissertation Research: Schyler Nunziata: Estimating the genetic and demographic response of an amphibian metapopulation to global climate change

Overview: Genetic approaches of estimating effective population size (Ne) are useful in conservation, ecology, and evolution, providing information on population abundance and demographic history, and insight into the evolutionary history and genetic viability of populations. However, before these estimates can be applied, the roles of both drift and migration on Ne must be accounted for. The overall goal of the proposed project is to address the role of metapopulation structure on local population processes, as well as on population viability in the face of climate-mediated environmental change at the metapopulation level. Collectively, the following questions will be addressed: (1) How are subpopulation estimates of genetic Ne impacted by gene flow and metapopulation structure? (2) How are Ne and genetic diversity impacted by climate-mediated variance in annual recruitment using a stochastic population model? How does metapopulation structure mediate population viability? The first question will be addressed by genetically sampling wetland populations surrounding a focal population, Rainbow Bay, from which I have collected time-series genomic data from two salamander species, A.opacum and A. talpoideum, with differing responses (growth vs. decline) to climate-mediated reduction in hydroperiod. Metapopulation samples will be used to characterize gene flow between wetlands and overall population structure, and will be incorporated into estimates of Ne at Rainbow Bay. These gene flow estimates will then be used as parameter inputs to address my second set of questions. I will develop projection models to predict whether the entire metapopulation is at risk for extinction under predicted climate change, or if only individual subpopulations are expected be lost. Intellectual Merit : The proposed projects will build on the existing knowledge of how demographic processes influence genetic diversity over contemporary time scales. The effectiveness of genetic monitoring relies on the ability of models to accurately reflect demographic trends over short time periods so that proper management actions can be applied. This is especially complicated in long-lived iteroparous species, which are often continuously distributed or exist in metapopulations across a landscape. This work will facilitate an understanding of how well genetic estimates of subpopulation Ne perform with incorporation of migration estimates, potentially leading to the design of more informative genetic monitoring techniques. By using a complementary approach of mark-recapture, temporal and metapopulation level genetic sampling, and computer simulations, I will be able to thoroughly assess how genetic-diversity is impacted by climate change, life-history, and demography in salamanders. Broader Impacts : This work takes advantage of a massive amount of mark-recapture data and related studies in a long-term field site, Rainbow Bay on the Savannah River Site. This data set is invaluable for studies of amphibian communities, especially in times of intense environmental change. It is also a substantial extension to co-PI Nunziata?s dissertation work, providing opportunities for graduate and undergraduate training in bioinformatics, mark-recapture data analysis, and population modeling. Co-PI Nunziata has trained undergraduates in laboratory and genomic analysis techniques, resulting in co-authored publications, and is in a position to engage under-represented undergraduates from rural Appalachia here in Kentucky. This research is of broad interest to population ecologists and evolutionary biologists, and will contribute to a greater understanding of the interplay of demography, life-history, and genetic diversity.