Genetic diversity and distribution of the ringed salamander (ambystoma annulatum) across multiple spatial scales
Species distributions are governed by a complex suite of abiotic and biotic interactions that govern movement of individuals and are variable through time and space. These dynamic processes, such as shifts in temperature and precipitation regimes throughout geologic time, in conjunction with the species physiological constraints are strong regulators of local population dynamics, and thus the global abundance and distribution of a species. Since shifts in distributions leave lasting effects on the genetic diversity and structure of a species, genetic tools can be used to infer the contemporary and historic rates of movement using gene flow as a proxy. ... Across its distribution, I found that A. annulatum exists as two genetic clusters that correspond to watershed boundaries. Within each cluster, I found evidence for decreased gene flow in recent generations, possibly due to the extensive timber harvest and land conversion of the CIH post European settlement. Over smaller spatial scales, I found lower gene flow for A. annulatum and A. opacum, two fall breeding species, as compared to two spring breeding species (A. maculatum and N. v. louisianensis) across the same focal landscape. Across all four species, I identified marginal support for landscape resistances describing gene flow better than distance alone; however, I found that breeding phenology appears to be a stronger predictor of genetic differentiation. Finally, I found that the suggested terrestrial buffer zone recommendations (i.e., "life zones") do not sufficiently protect the majority of adult A. annulatum adults emigrating from ponds. Overall, these studies suggest that managing amphibian species requires indepth knowledge of the ecology and life history of a species.
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