Distribution, Dispersal and Dynamics of Amphibian Populations

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My research program is guided by the need to better comprehend how biological diversity gets distributed and maintained, particularly in view of the current ecological crises of biodiversity loss and biological invasions related to anthropogenic environmental change. The dynamic ecological processes that govern population viability and persistence are also fundamental to determining the distributions of species and the dynamics of species' ranges. The causative link between population-level dynamics and range-level dynamics is dispersal. When environmental conditions change quickly, populations may not be able to adapt rapidly enough to cope. Those that cannot adapt must disperse to survive. This is thought to be especially pertinent to animals with biphasic life histories, such as amphibians, since they are subjected to two differing selection regimes as larvae and adults during their lives. Because of their need for aquatic breeding habitats, amphibians have characteristically limited dispersal abilities and strong site fidelity. How is it possible, then, for such animals to colonize new habitats to the extent that they do, occupy large geographic ranges and survive environmental change? Using amphibians as my subjects, my objectives for the next five years are to reconcile patterns of amphibian distribution with the complexities of their population ecology and true potential for dispersal. I will test for the ecological consequences of biphasic life histories using field experiments with larvae in experimental ponds and juveniles in terrestrial enclosures under varying conditions of density and competition. I will test dispersal vs. site fidelity in toads by manipulating breeding site and refuge availability and tracking individual animal movements. I will use this understanding of dispersal potential to ask how amphibian species ranges respond to climatic changes using species distribution models validated against the historical record of northward range expansion. These projects provide opportunities for training highly qualified personnel. My research program will substantially contribute towards understanding the dynamics of populations, the dispersal of individuals and the biology of species' ranges.