Pleistocene glaciations and mitochondrial diversity evolution in the Atlantic salmon

Fluctuating Pleistocene landscapes and environments, involving glaciation cycles, have repeatedly shifted species’ distributions in the Northern Hemisphere, driving an evolutionary meta-population dynamic of local population extinctions and recolonizations, including contractions into, expansions out of, glacial refugial areas. We address this question in the Atlantic salmon by developing an independent phylogeographic hypothesis (IPH) for the eastern part of its North Atlantic range from a consideration of regional Pleistocene environmental change and the species’ life-history, distributional and dispersal biology. We test the IPH using a collated mitochondrial SNP data set for ~13,000 individuals from ~200 river systems. The observed diversity largely accords with the IPH and provide novel insight into how glaciation dynamics condition diversity evolution in the species.