Molecular Systematics of the Lampsilini (Bivalvia: Unionoida): Evolution of Ancient Sex-Specific Extension of the cytochrome c oxidase II Gene

肯特州立大学的Walter R.Hoeh博士获得了DEB-0237175A资助，用于研究淡水贻贝(双壳类)部落Lampsilini的分子系统学和线粒体DNA(MtDNA)遗传。在海洋和淡水贻贝中发现了线粒体DNA的双亲遗传。这一系统在海洋贻贝中得到了广泛的研究，但对物种丰富的淡水动物的研究相对较少。对双亲遗传系统的研究表明，线粒体DNA性别转换事件在海洋贻贝中很常见；然而，最近的研究表明，这种性别转换事件在淡水贻贝中是不存在的。这种情况可能与淡水贻贝雄性传播的线粒体DNA中COII基因600个核苷酸的延伸有关。利用DNA测序技术，这个项目将研究Lampsilini中COII延伸的进化，Lampsilini是一组特别令人感兴趣的淡水贻贝，因为它包含了双壳类中一些最有趣的形态适应，以及在这个部落内的一个物种中COII延伸的二次减少。该项目的具体目标包括：(1)构建灯盏花素系统发育的可靠估计，(2)研究COII延伸减少的进化模式，以及(3)研究男性和女性传递的mtDNA的分子进化。这些目标将有助于对灯火线进化关系的测试，确定COII延伸的不稳定，确定COII延伸防止性别转换的程度，并增加我们对分子进化变化背后的力量的理解。这些具体目标的完成具有广泛的影响，包括：世界上最濒危的动物群之一淡水贻贝的保护；双亲和标准母体mtDNA遗传的进化；Lampsilini的形态性别二型性的进化；以及分子进化的机制。此外，拟议的研究将为一名年轻的进化论者/系统论者提供培训。

AbstractDEB - 0237175A grant has been awarded to Dr. Walter R. Hoeh at Kent State University to study the molecular systematics and mitochondrial DNA (mtDNA) inheritance in the freshwater mussel (bivalve) tribe Lampsilini. Doubly-uniparental inheritance of mtDNA has been found in marine and freshwater mussels. This system has been studied extensively in marine mussels but relatively little work has been done on the species-rich freshwater fauna. Studies of the doubly-uniparental inheritance system indicate that mtDNA gender-switching events are common in marine mussels; however, recent work suggests that these gender-switching events are absent in freshwater mussels. This situation may be related to a 600 nucleotide extension of the COII gene in freshwater mussel male-transmitted mtDNA. Using DNA sequencing techniques, this project will examine the evolution of the COII extension in the Lampsilini, a group of freshwater mussels that are of particular interest because it contains some of the most interesting morphological adaptations within bivalves as well as a secondary reduction of the COII extension in a species within this tribe. This project's specific objectives include: (1) construct robust estimates of lampsiline phylogeny, (2) investigate the evolutionary pattern of reduction of the COII extension, and (3) examine the molecular evolution of the male- and female-transmitted mtDNAs. These objectives will facilitate tests of lampsiline evolutionary relationships, determine the lability of the COII extension, determine the extent to which the COII extension prevents gender-switching, and increase our understanding of the forces underlying molecular evolutionary change. The completion of these specific objectives has broad implications, including: conservation of freshwater mussels, one of the most imperiled faunas in the world; the evolution of doubly-uniparental and standard maternal mtDNA inheritance; evolution of morphological sexual dimorphism in the Lampsilini; and mechanisms underlying molecular evolution. In addition, the proposed research will provide training for a young evolutionist/systematist.