Genetic structure of redback salamander Plethodon cinereus populations in continuous and fragmented forests

Fragmentation of natural habitats is increasing dramatically, yet its effects on the distribution of genetic variation in wild populations remain largely unknown. In this study, two woodland populations of the redback salamander Plethodon cinereus in Connecticut, USA, were contrasted using molecular and morphological markers. One population was from a landscape fragmented for 300 yr by human activities and another from a nearby, undisturbed landscape. Genetic differentiation, based on molecular markers, was marginally greater in the fragmented population than in the contiguous population, and, within the fragmented population, was greater among subpopulations lacking historical forest connections. Genetic divergence between subpopulations was also weakly related to geographic distance in the population occupying continuous forest, but not in the population occupying fragmented forest. Fragmentation enhanced morphotype diversity within populations of P. cinereus, whereas levels of molecular genetic diversity within subpopulations were apparently unaffected.