Conservation and management of peripheral populations: Spatial and temporal influences on the genetic structure of wood frog (Rana sylvatica) populations

Peripheral populations of wide-ranging species are often of special conservation concern, and knowledge of genetic diversity, gene flow, and historical population dynamics are critical to informed management of these populations. In this study we evaluate patterns of genetic diversity and gene flow among a series of wood frog populations in east-central Missouri where it is a species of conservation concern. Because these populations are on the periphery of the species’ range and are isolated from one another by fragmented landscapes, we expected to see population subdivision with signatures of range-edge effects and isolation by resistance. Our analyses reveal significant interpopulation differentiation and a distinct gradient in diversity where levels of allelic richness and heterozygosity decline as the species boundary is approached. These patterns likely stem from factors characteristic of peripheral populations, including reduced population size, reduced gene flow, and more frequent extinction–recolonization events. Population structure was evident, but isolation by resistance (i.e. fragmentation) was not a significant factor in our focal landscape. Isolation by distance was significant, but the level of population differentiation suggests that gene flow among populations is limited. We hypothesize that the lack of gene flow is due to the absence of available fishless breeding habitats outside of protected, managed lands, and recommend that future management efforts of the wood frog include increasing population connectivity at the landscape scale via the creation and maintenance of fishless aquatic breeding habitat.