Population structure and gene flow in a heavily disturbed habitat: implications for the management of the imperilled Red Hills salamander (Phaeognathus hubrichti)

摘要

Estimating levels of gene flow and assessing levels of population connectivity are of critical importance to the field of conservation genetics, especially for imperiled species. Many factors can influence dispersal and therefore gene-flow patterns across a natural landscape. These patterns can be substantially altered by the impacts of habitat modification by humans or natural phenomena. Landscape-genetic studies that address both historical and contemporary influences on gene flow can be critical to demonstrating whether isolated populations with low levels of genetic variation are typical of the species or a result of strong negative effects of such modification. We used 10 microsatellite markers to investigate the spatial genetic patterns of the Red Hills salamander (Phaeognathus hubrichti), a federally listed species. Bayesian clustering revealed five well-supported demes within the range of P. hubrichti. Gene-flow analysis suggested that overall migration levels for P. hubrichti are low, but coalescent methods indicate that migration levels were significantly higher before habitat modification by humans. By accounting for history and species characteristics, our results suggest that loss and fragmentation of habitat have strongly negatively affected P. hubrichti by reducing migration, increasing bottlenecks, and promoting high levels of inbreeding.