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

圣路易斯大学的罗伯特·伍德博士和安德鲁·金齐格先生获得了一项研究Cottus属的拨款；Cottus是一种头部扁平、胸鳍增大的小型底栖鱼。在北美、日本和欧亚大陆的淡水和海洋环境中，Cottus总共由大约42个物种组成。该属是北美鱼类区系中研究最少的组成部分之一。阻碍对Cottus进化生物学更全面了解的主要问题包括：(1)缺乏关于该属成员之间关系的假设；(2)关于该属物种的确切数量的不确定性；以及(3)该属成员是否形成一个有凝聚力的或合乎逻辑的群体的问题。为了解决这些问题，研究人员建议使用2619个碱基的DNA序列数据来生成一个关于Cottus物种之间关系的假说。这种关系假说将为解决上面讨论的三个主要问题提供基础，并允许评估两个有趣的进化问题。首先，这一假说可以用来重建海洋和淡水环境之间过渡的进化史，这是一种有趣的进化现象，因为它涉及到几个允许有机体应对极端不同环境的生理机制的修改。其次，系统发育假说可以用来评估导致该属成员的物种形成和分布的假说：(1)超大陆盘古大陆的分裂；(2)由大陆桥建立的联系；以及(3)淡水和海洋环境之间的扩散。此外，研究人员提出的工作将为未来关于山雀进化生物学的研究提供框架，并提供有关受保护的山雀物种的重要信息。

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.