Evolution of codfishes (Teleostei: Gadinae) in geographical and ecological space: evidence that physiological limits drove diversification of subarctic fishes

Aim: To develop a holistic biogeographical history of codfishes in the subfamily Gadinae based on historical relationships, ecological niche, and evolution of physiological tolerances. Two alternative diversification scenarios were tested in two co-distributed, Northern Hemisphere clades: (1) clade ancestors were temperate, and environmental niche has been conserved over evolutionary time, implying that speciation was driven by vicariance associated with ice sheet formation; and (2) clade ancestors were Arctic, and species convergently adapted to temperate environmental conditions, implying that speciation was driven by repeated adaption to temperate environments. Location: Northern Hemisphere Arctic and subarctic oceans. Methods: Fifty-five new sequences of four genes from 23 tissue samples were combined with 10 GenBank sequences to generate a time-calibrated phylogenetic hypothesis. Combining the phylogeny with information on species' ecological niche tolerances inferred from correlat...