Dissertation Research: Molecular Systematics and Historical Biogeography of the Holarctic Fish Genus Cottus (Scorpaeniformes: Cottidae)

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A grant has been awarded to Dr. Robert Wood and Mr. Andrew Kinziger of Saint Louis University to study the genus Cottus; a group of small benthic fishes with flattened heads and enlarged pectoral fins. Cottus is comprised of approximately 42 total species inhabiting both freshwater and marine environments in North America, Japan, and Eurasia. The genus is one of the most poorly studied components of the North American fish fauna. Major problems preventing a more complete understanding of Cottus evolutionary biology include: (1) lack of a hypothesis of relationships among members of the genus; (2) uncertainty concerning the exact number of species in the genus; and (3) questions as to whether the members of the genus form a cohesive or logical group. To address these problems the investigators propose to generate a hypothesis of relationships among Cottus species using 2619 bases of DNA sequence data.The hypothesis of relationships will provide a foundation to address the three major problems discussed above and allow for the evaluation of two interesting evolutionary questions. First, the hypothesis can be used to reconstruct the evolutionary history of transitions between marine and freshwater environments, a fascinating evolutionary phenomenon because it involves modification of several physiological mechanisms that allow organisms to cope with extremely different environments. Second, the phylogenetic hypothesis can be used to assess hypotheses responsible for the speciation and the distribution of members of the genus: (1) the break up of the supercontinent Pangea; (2) connections created by land bridges; and (3) dispersal between freshwater and marine environments. Further, the investigators proposed work will provide the framework for future research on Cottus evolutionary biology and furnish important information concerning those Cottus species of conservation concern.