Phylogeographic Structure in Mitochondrial Dna of the Lake Whitefish (Coregonus Clupeaformis) and Its Relation to Pleistocene Glaciations

Restriction-fragment length polymorphisms were employed to evaluate the phylogenetic relationships, the genetic diversity and the geographic structure in mitochondrial DNA (mtDNA) lineages of the lake whitefish, Coregonus clupeaformis. Thirteen restriction enzymes that produced 148 restriction fragments were used to assay mtDNAs of 525 specimens collected among 41 populations. The sampling covered the entire range of the species, from Alaska to Labrador. Four distinct phylogeographic assemblages were identified. The Beringian assemblage, confined to Yukon and Alaska, was phylogenetically distinct from other assemblages and exhibited the highest level of nucleotide diversity. The Acadian assemblage was confined to southeastern North America and composed of a unique mtDNA clade. The Atlantic assemblage was confined to southern Québec and the northeastern United States and was also observed among anadromous populations of northern Hudson Bay. This group was highly polymorphic and responsible for most of the mtDNA diversity observed outside Beringia. The Mississippian assemblage occupied most of the actual range of lake whitefish, from the Mackenzie delta to Labrador. Ninety-two percent of all whitefish of this proposed origin belonged to a single mtDNA haplotype. Overall, the diversity, the geographic structure and the times of divergence of mtDNA phylogenetic assemblages correlate with the Pleistocene glaciations classically assumed to have dramatically altered the genetic diversity of northern fishes in recent evolutionary times. Our results emphasize the dominant role of these catastrophic events in shaping the population genetic structure of lake whitefish.