Data from: 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
interpret patterns of phenotypic evolution. Results: The occurrence of
multiple mtDNA groups suggests that highly prickled inland phenotypes
comprise more than one genetic lineage. Both mtDNA and microsatellite data
are consistent with post-glacial dispersal along the coast and repeated
coastal to inland colonization events, as opposed to inland dispersal of a
single lineage from a southern refugium to northern regions. Main
conclusions: Our results suggest that highly prickled inland phenotypes
evolved repeatedly following multiple inland colonization events, probably
via coastal rivers. The prickly sculpin therefore provides an example of
recent (post-glacial) parallel evolution, potentially facilitated by
standing genetic variation already present in the ancestral coastal
populations.