Comparative Phylogeography and Ecological Niche Modeling of Two Sister Species of Freshwater Sculpin in California's Great Central Valley

Historical and contemporary factors influencing species distribution are often encapsulated within their genomes.  Within California’s Great Central Valley, these factors are intensive, owing to the region’s geologic and anthropogenic influences.  Two species of endemic freshwater sculpin, Cottus gulosus and C. pitensis, stand to be good indicators of freshwater environments based on their distributions.  Using nuclear and mitochondrial markers, we investigated the phylogeographic relationships within and between species. Distinct lineages were often associated with historical biogeographic separations and breaks.  Higher levels of intraspecific structure were found within C. gulosus when compared to C. pitensis, suggesting a major role of historical hydrologic conditions in creating discrepancies between species.  To address contemporary factors, ecological niche models were developed using abiotic components (temperature, precipitation, etc.) to predict species distributions.  Initial models were found to reasonably predict current species distributions and were largely contingent upon spring precipitation and maximum temperature.  Future comparisons with other native sympatric species hold promise for improving the understanding of this region, as well as the conservation and management of all regional ichthyofauna.