Limited genetic structure in a wood frog (Lithobates sylvaticus) population in an urban landscape inhabiting natural and constructed wetlands

Abstract

Urbanization has been linked to amphibian population declines globally. Habitat fragmentation can negatively impact gene flow among populations but what role artificially constructed wetlands have in maintaining gene flow in urban amphibian populations remains uncertain. We assessed gene flow in a population of wood frogs (Lithobates sylvaticus) inhabiting both constructed and natural wetlands located in Edmonton, Alberta, Canada. We genotyped 10 microsatellite loci in 182 frogs from eight wetlands and tested for genetic differentiation between wetlands. We tested if bottlenecks had occurred at constructed wetlands and if there were differences in allelic richness between natural wetlands and constructed wetlands. We found no evidence of bottlenecks, no differences in allelic richness among subpopulations, and no genetic structure within the population. Although significant differences in pair-wise comparisons of allele frequency distributions between wetlands were detected, all F ST values were low (0.003–0.053) and Bayesian clustering indicated the presence of a single genetic cluster. Despite extensive urbanization within our study area, genetic homogeneity has been preserved indicating that it may be possible to use constructed wetlands to maintain amphibian populations and preserve gene flow among subpopulations living within urbanized landscapes.