Sculpins of the West: A molecular taxonomy of Cottus in western North America

Data Crowd Sourcing

Thanks to contributions by over 130 biologists, academicians, students, and citizen scientists, we received over 8,300 specimens–representing every described species–from over 1,500 locations in every state and province across western North America to which sculpin were native. We sequenced 1–4 genes for one or more sculpins from every location (over 4,000 sculpins in all). We supplemented those data with sequences downloaded from public sequence libraries, which were georeferenced by using data in those libraries, consulting the publication with which the specimens were associated, or searching records of museums with substantial ichthyological collections. We also included specimens of two species from eastern North America, C. bairdii and C. cognatus, that were believed to be present in western North America, and the type species for the genus, C. gobio, from Europe.

Phylogenetic Trees

We are using genetic tools to clarify the identity and relationships among species. These include phylogenetic trees based on genetic sequences and are in NWK and PDF format.

Key Findings

• The current taxonomy recognizes 19 species from the region. We hypothesize that there are 37 species in 8 species complexes in western North America. These represent heretofore unrecognized species, previously recognized taxa resurrected from synonymy, and most of the currently recognized species.
• Nearly all species can be diagnosed with a single mitochondrial gene. Knowing where a specimen was collected is nearly as informative.
• A handful of currently recognized taxa showed little or no genetic differentiation from other species. We acknowledge that these taxa might be valid under other species concepts.
• Hybrids among sculpin are common, and some species are of ancient hybrid origin.
• Neither C. bairdii nor C. cognatus are found in western North America. We did propose, however, three new species within the former from eastern North America, and suspect that there may be others.