Genetic Assessment Reveals Population Fragmentation and Inbreeding in Populations of Brook Trout in the Laurel Hill of Pennsylvania

Abstract

AbstractWhether natural or man‐made, landscape features often influence the patterns of genetic variation within a species and can have important conservation implications. This is especially true for Brook Trout Salvelinus fontinalis, which are typically restricted to high‐quality headwater streams. In this study, we characterized the patterns of genetic partitioning and diversity among Brook Trout populations in the Laurel Hill of southwestern Pennsylvania with respect to landscape features and potential barriers to migration. In total, 354 wild Brook Trout samples collected across 10 streams were analyzed using 12 microsatellite loci. Our results showed a wide range of genetic diversity (allelic richness AR = 3.404–7.124; expected heterozygosity He = 0.432–0.727) and effective population size estimates (Ne = 13.5–1,106.6) and indicated that some sites contained small, low‐diversity populations of Brook Trout. Three populations were located upstream of reservoirs; however, our results did not show significant differences in the genetic diversity metrics between upstream and downstream populations. Although isolation by distance could be a factor, the patterns of genetic differentiation revealed minimal contemporary gene flow between watersheds and among most streams. Overall, our results highlight the need for continued population monitoring and habitat restoration for Brook Trout populations in southwestern Pennsylvania.