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Conservation Genetics


For many amphibian species, reduced landscape connectivity results in reduced genetic connectivity among populations. However, large efective population sizes (Ne) slow the rate of genetic drift, causing subdivided populations to remain genetically similar despite little gene fow among them. Therefore, it is important to address the combined efects of Ne and matrix permeability to quantify the relative importance of gene fow and genetic drift on isolated amphibian populations.

We applied a landscape genetic approach to investigate how patterns of gene fow (m), Ne (inferred via θ) and genetic difer- entiation difer among Eastern Red-backed Salamander (Plethodon cinereus) populations in a fragmented landscape (n=4)

compared to a continuous forest (n=4). We assayed a panel of 10 microsatellite markers for population genetic analyses.

Additionally, we constructed and validated a distribution model to generate resistance surfaces for examining the relation- ship between landscape connectivity, m, θ, and genetic diferentiation (FST) using maximum-likelihood population-efects

models (MLPE). Populations in continuous habitat were undiferentiated, whereas fragmented populations exhibited genetic structure driven by a single population. Results of the MLPE models in the fragmented landscape revealed spatial variation in θ as the best predictor of pairwise FST, followed by estimates of m, suggesting migration-drift interactions have a stronger infuence on genetic diferentiation than matrix permeability. Moreover, model coefcients for landscape resistance were comparable between landscapes. Overall, our results provide insight as to how the interaction of gene fow and genetic drift shapes population structure for a dispersal-limited species within a predominately anthropogenic landscape.