Mitochondrial Variation in Western North American Burbot with Special Reference to the Kootenai River in Idaho and Montana
Madison Powell, Vaughn L. Paragamian, and Jim Dunnigan
Abstract.— Burbot Lota lota are the only freshwater members of the cod family Gadidae and possess a circumpolar distribution. Studies of phylogenetic relationships between palearctic and nearctic burbot have demonstrated the presence of distinct groups between North American and European populations. Higher resolution separation within western North American populations has thus far not been undertaken. In this study, we examined 372 burbot collected from 28 sample locations across its range in western North America. A 572 base pair portion of the mitochondrial cytochrome b gene was used to estimate diversity and divergence among populations and further characterize matrilineal lines. Three distinct haplogroups of burbot were observed that correspond to past allopatric distributions within Pleistocene refugia, namely the Pacific, Mississippi, and Missouri. Within the Columbia/Kootenai River basins west of the Continental Divide, admixtures of Pacific and Mississippi matrilines are indicative of both postglacial expansion and sorting as well as clinal variation resulting from vicariant events as seen in the Kootenai River population below Kootenai Falls. The study was also designed to help determine which northwest population would be most suitable in genetic terms as a donor stock to rehabilitate the Kootenai River, Idaho population. Of eight haplotypes found in the Kootenai River, Idaho and Columbia Lake, British Columbia, six are shared.