Comparing microsatellites and single nucleotide polymorphisms to evaluate genetic structure and diversity in wolverines (Gulo gulo) across Alaska and western Canada

The Wolverine (Gulo gulo) is a cold-adapted species of conservation interest because it is sensitive to human development, disturbance, exploitation, and climate warming. Wolverine populations have been studied across much of their distributional range to evaluate patterns of genetic diversity, genetic structure, and gene flow. Little population structure has been detected in northwestern North America with microsatellite loci, but low genomic diversity in wolverines may limit detection of genetic differences in this highly vagile species. Here, we genotyped a relatively large sample of wolverines from across Alaska (US) and adjacent Yukon (Canada) with 12 microsatellite loci (n = 501) and 4,222 single nucleotide polymorphisms (SNPs; n = 201) identified using restriction-site associated DNA sequencing. We compared the relative ability of our microsatellite and SNP datasets to evaluate population genetic structure, genetic diversity, differentiation, and isolation by distance (IBD). We predicted that the SNP dataset would detect a higher degree of genetic structure and provide more significant support for IBD. We found evidence for multiple genetic clusters, including genetic distinctiveness of wolverines in southeast Alaska and on the Kenai Peninsula. The SNP dataset detected additional genetic clusters that align largely with ecoregions, and the SNP dataset showed stronger evidence of IBD, while the 2 datasets were generally consistent in estimates of genetic diversity and differentiation among regional groups. Our results highlight the importance of genomic methods to assess gene flow in wolverines. Identifying population genetic structure allows an assessment of the potential impacts of conservation threats and is an important precursor for designing population monitoring programs. Increasing the number and density of genetic loci has increased the resolution of population structure analysis in wide-ranging mammal species. This study assesses genetic population structure, isolation by distance (IBD), and genetic diversity for the North American Wolverine across their continuous northwestern range with 12 microsatellite loci and 4,222 single nucleotide polymorphisms (SNPs), finding that SNPs have more power to describe population structure and IBD. Population groups identified with SNPs largely align with ecoregions and geographic features, and we recommend monitoring efforts on populations with lower genetic diversity.