Genetic Subdivision and Connectivity of Lake Trout Populations in Southern Lake Superior

There are three lake trout morphotypes in Lake Superior; the lean, humper and siscowet.  These morphotypes are characterized by differences in morphology, growth, lipid levels, diet, habitat and gene expression.  Leans primarily inhabit shallow water areas of Lake Superior, the siscowet or “fat” form is found in the deep-water habitat of the lake while the humper is associated with offshore reefs.  We sampled siscowet and lean lake trout from the Michigan waters of southern Lake Superior and used microsatellite loci to characterize the connectivity between sampling locations in southern Lake Superior.  Deviations from Hardy-Weinberg proportions resulting from a deficiency of heterozygotes were observed for many of the sampled groups in this analysis, suggesting that lake trout may form aggregations made up of individuals originating from multiple genetic populations.  These patterns have led us to use multivariate methods to analyze the composition and connectivity of these admixtures.