Genetic distances among population of Atlantic Cod (Gadus morhua) in the North Atlantic

Among samples in the Northwest Atlantic, Flemish Cap is most distinct: this offshore seamount was exposed during the last glacial period and probably represented a refugial cod habitat. Allele frequency distributions in the Northwest Atlantic are otherwise unrelated to geographic distributions. Samples from south of the Laurentian Channel cluster as closely with samples from north of the channel as they do with each other and are no more similar (or just as dissimilar) to each other than are replicate samples taken in the same year from different locations in Trinity Bay, Newfoundland. Populations of cod in the Northeast Atlantic and Barents Sea are genetically distinct from those in the Northwest Atlantic. Patterns within Norwegian cod populations appear to be much more highly differentiated over much shorter geographic distances than in the Northwest Atlantic. Pairwise distances between replicate samples from Tromsö or the Barents Sea are substantially greater than those between any pair of samples taken in the Northwest Atlantic. [UPGMA distance analysis of Rogers’ Distance]