DISSERTATION RESEARCH: Estimating the genetic and demographic response of an amphibian metapopulation to global climate change

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This project will contrast the utility of population size estimates and migration estimates in predicting population declines and increases. It is known that populations that are too small can experience high levels of inbreeding and may lose much of their genetic diversity over time. In turn they may face higher extinction probabilities and for this reason population size could be a critical variable in many conservation plans. Population size, however, may be a poor predictor of a population's viability when additional forces are at play. Migration between locations as well as climate induced fluctuations in a population from year to year may be just as important as the average population size in predicting long term trends in a population's likelihood of survival. The researchers will examine the relative effectiveness of average population size, migration between populations and population variability in predicting the viability of populations of two salamander species. The project will develop more informative genetic monitoring techniques as well as the training of a doctoral student.This project will determine the effective population size (Ne), and gene flow patterns of two salamander species that have been monitored in the same wetland for 37 years. One of the species, Ambystoma opacum, is increasing in number while the other, Ambystoma talpoideum, is decreasing in number over the last fifteen years. This study will answer two questions: First, is the reliability of Ne as a predictor of population viability dependent on metapopulation structure? Second, how do gene flow and annual fluctuations in reproductive rate influence the long-term viability of populations? The question of how gene flow impacts viability estimates based on Ne will be addressed by collecting Single Nucleotide Polymorphism data from individuals from five connected subpopulations using next generation sequencing. Maximum likelihood estimates of Ne for the subpopulations, and Bayesian estimates of gene flow rates between the subpopulations will be calculated for both species. The importance of metapopulation structure in refining conclusions based on Ne will be determined for both declining and growing populations from that data. Individual based census data from previous years will be used to ground truth estimates obtained from genetic samples. Projection models will then be developed to predict whether the metapopulation of each species is at risk for extinction or if only individual subpopulations are expected be lost and recolonized over time.