A methodological approach to the genetic identification of native Brook Trout (Salvelinus fontinalis) populations for conservation purposes

Abstract

As biodiversity is transformed on a global scale, identifying and protecting populations unaffected by habitat disturbances is essential to ensuring natural genetic diversity is not irretrievably lost. Furthermore, knowledge of the interactions between endemic populations and human-introduced conspecifics is imperative to the creation of management strategies that conserve and enhance population viability. In this study, these issues were examined for Brook Trout (Salvelinus fontinalis) populations from the Northeastern United States through the characterization of the spatial genetic structure of over 2000 wild fish, collected from 83 different sampling locations, and encompassing 18 individual watersheds. Population genetic analyses of microsatellite data at 13 loci demonstrate that, despite centuries-long stocking practices, roughly half of the populations examined exhibit genetic structure consistent with native origins. In addition, when examining the populations that revealed influence from stocked con-specifics, only a limited proportion of ancestry was attributed to stocked fish in the majority of cases. The methodological approach presented in this study for identifying native populations demonstrated strong population subdivision within and among populations, watersheds, and drainage basins. These findings are consistent with past inferences regarding native population structure of cold-water fish species and represent a detailed accounting of the remaining Brook Trout populations still intact in their native waters. Furthermore, the extent of such populations greatly exceeds what had been previously identified and prioritized as ‘heritage’ based on stocking history. The methods and data presented here may serve as an important tool to inform diversity maintenance, species recovery planning, and biodiversity conservation in this and other genetically unique and historically important native species. Keywords: Conservation genetics, Salvelinus fontinalis, Landscape heterogeneity, Introgression, Biogeography, Native species conservation