Population ecology of Ambystoma tigrinum (Caudata, Ambystomatidae) and occupancy dynamics in an Appalachian pond-breeding amphibian assemblage

The distribution and abundance of species are shaped by how individuals within populations contend with changes in their environment. Revealing the processes that underlie population dynamics therefore require estimates of spatiotemporal changes in survival, movement, and reproduction. I took three approaches towards uncovering how life-history and environmental changes interact to determine the dynamics of pond-breeding amphibian populations in a complex of natural sinkhole ponds in west-central Virginia, USA. I studied the population ecology of the eastern tiger salamander, Ambystoma tigrinum tigrinum, across three populations and over four years to determine how differences in hydrological conditions among breeding ponds and across years within ponds influence adult vital rates. I used estimates of these vital rates to build population projection matrices to study how local populations and the regional metapopulation are likely to respond to different long-term changes in climate and to reveal what events in the complex life cycle of these animals are most important to population viability. My estimates of Ambystoma tigrinum vital rates suggest that populations may be locally adapted to the variation in reproductive success imposed by the local interaction of pond hydrology and weather. Projections of these populations reveal that the asynchrony of these demographic variables is critical to population viability and that, despite having low rates of movement and a life-history that invokes a storage effect, the regional persistence of the species is dependent on demographic links between populations. I also took a broader taxonomic and regional approach by examining how the hydrological history of 32 ponds determines which of 14 amphibian taxa are likely to colonize and disappear from a pond's assemblage of species. This study revealed patterns in how life history, pond hydrology, and weather interact to determine the community dynamics of pond-breeding amphibians in temporary ponds.