Incongruence between mtDNA and nuclear data in the freshwater mussel genus Cyprogenia (Bivalvia: Unionidae) and its impact on species delineation

Accurately identifying species is a crucial step for developing conservation strategies for freshwater mussels, one of the most imperiled faunas in North America. This study uses genetic data to re-examine species delineation in the genus Cyprogenia. Historically, Cyprogenia found west of the Mississippi River have been ascribed to Cyprogenia aberti (Conrad 1850), and those east of the Mississippi River were classified as Cyprogenia stegaria (Rafinesque 1820). Previous studies using mitochondrial DNA sequences indicated that C. aberti and C. stegaria were not reciprocally monophyletic groups, suggesting the need for systematic revision. We generated a novel dataset consisting of 10 microsatellite loci and combined it with sequence data from the mitochondrial ND1 gene for 223 Cyprogenia specimens. Bayesian analysis of the ND1 nucleotide sequences identified two divergent clades that differ by 15.9%. Members of these two clades occur sympatrically across most sampling locations. In contra...精准物种鉴定是制定淡水蚌保护策略的核心环节，淡水蚌为北美濒危程度最高的动物类群之一。本研究依托遗传数据，重新探讨弓背蚌属（Cyprogenia）的物种界定问题。历史上，密西西比河以西发现的弓背蚌属物种被归为阿氏弓背蚌（Cyprogenia aberti，Conrad, 1850），而密西西比河以东的类群则被划归为斯特氏弓背蚌（Cyprogenia stegaria，Rafinesque, 1820）。既往基于线粒体DNA（mitochondrial DNA）序列开展的研究显示，阿氏弓背蚌与斯特氏弓背蚌并非互为单系群，这表明有必要对该类群开展系统性分类修订。本研究构建了一套包含10个微卫星位点（microsatellite loci）的全新数据集，并将其与223份弓背蚌属标本的线粒体ND1基因序列数据进行整合。对ND1核苷酸序列的贝叶斯分析（Bayesian analysis）识别出两个遗传分化度达15.9%的演化支（clades）。这两个演化支的类群在绝大多数采样点均呈同域分布。然而……