The Genetic Effects of Urbanization and Habitat Fragmentation on Spotted Salamander Ambystoma maculatu Populations

With the U.S. population now over 300 million and growing at a record rate, the natural landscape is being reduced and fragmented. Reductions in habitable land threaten the genetic health of native wildlife. Such a loss in genetic diversity can negatively affect a population’s ability to keep pace with long-term environmental changes, as well as shortterm changes induced by humans. Genetic diversity can be measured in terms of differences in DNA composition. Microsatellites are short sequences of highly variable DNA, which makes them ideal markers for investigating overall genomic diversity within and among populations. Microsatellites, thus, can serve as molecular indicators of genetic health, connectivity, and reproductive potential of populations. We chose five microsatellite loci to determine the effects of habitat fragmentation on a network of spotted salamander (Ambystoma maculatum) populations in the greater Charlotte, North Carolina area. We addressed two primary hypotheses: (1) degree of connectedness among populations across the fragmented landscape is inversely related to distances between populations and intensity of urbanization and (2) genetic variation within populations is inversely related to level of degradation of surrounding habitat. To address these hypotheses, we studied five populations of salamanders that varied in distance from nearest neighboring population and in quality of surrounding habitat. We used GIS to quantify habitat and distance variables. Results will be discussed in the context of habitat management, specifically the need for establishment of metapopulations such that multiple populations and breeding ponds are interconnected by contiguous habitat