Complex phylogeography and historical hybridization between sister taxa of freshwater sculpin (Cottus).

Species ranges which span different geographic landscapes frequently contain cryptic species or population-level structure. Identifying these possible diversification factors can often be accomplished under a comparative phylogeographic framework. However comparisons suffer if previous studies are limited to a particular group or habitat type. In California, a complex landscape has led to several phylogeographic breaks, primarily in terrestrial species. However two sister taxa of freshwater fish, riffle sculpin (Cottus gulosus) and Pit sculpin (C. pitensis), display ranges based on morphological identifications which do not coincide with these breaks. Using a comprehensive sampling and nuclear, mitochondrial, and microsatellite markers, we hypothesized proposed species ranges are erroneous based on potential hybridization/gene flow between species. Results identified a phylogeographic signature consistent with this hypothesis, with breaks at the Coast Range Mountains and Sacramento/San ...