SPATIOTEMPORAL ANALYSIS OF GENE FLOW PATTERNS AMONG WOODLAND SALAMANDER POPULATIONS INHABITATING CONTRASTING LANDSCAPES

Dispersal is a fundamental evolutionary process that serves as a mechanism by which local populations remain connected through space. Habitat loss and fragmentation remain widespread threats to biodiversity globally, and therefore it is imperative to understand how dispersal patterns are affected by anthropogenic modifications of the environment. Using a panel of 10 novel microsatellite loci, I estimated gene flow patterns over historical and contemporary timescales among populations of Eastern Red-backed Salamanders (Plethodon cinereus) in a previously unstudied portion of the species range. Four focal populations reside within a highly fragmented urban center whereas the remaining four focal populations persist in a relatively continuous landscape. Among fragmented populations, I observed weak genetic structuring, primarily driven by a highly divergent population. In contrast, populations in the continuous landscape were genetically homogeneous. Temporal analysis of gene flow patterns within the fragmented landscape revealed little difference between historical and contemporary estimates, as well as gene flow estimates comparable to those observed in continuous habitat. These results suggest that the observed genetic differentiation is not a result of reduced gene flow following fragmentation. In the continuous landscape, temporal changes in gene flow indicate a re-routing in the directionality of the major source of historical migrants, likely corresponding to historical land use practices. In both landscape types, I found the contribution of historical processes to be important in shaping contemporary gene flow patterns, as well as gene flow occurring on a large scale within a fragmented landscape