Phylogeography of the prickly sculpin (Cottus asper) in north-western North America reveals parallel phenotypic evolution across multiple coastal–inland colonizations

Aim: Glacial cycles during the Pleistocene may have frequently contributed to parallel evolution of phenotypes across independently evolving genetic lineages associated with separate glacial refugia. Previous studies based on morphology suggested that the prickly sculpin (Cottus asper) survived the Last Glacial Maximum (LGM) in southern coastal and inland refugia, favouring allopatric divergence between coastal and inland prickling phenotypes, which vary in the degree to which spine-like scales cover the body of the fish. Herein, we aimed to test whether parallel evolution across multiple genetic lineages rather than a single-lineage origin of highly prickled inland sculpins could serve as an explanation for the biogeographical distribution of prickling phenotypes. Location: North-western North America, Southeast Alaska and Canada (British Columbia). Methods: We used data from mitochondrial haplotypes and 19 microsatellite loci to identify distinct genetic lineages as a basis to interpr...