1. The eastern pondmussel, Sagittunio nasutus (Bivalvia: Unionida), has declined in abundance and distribution in eastern North America over the last few decades. The declines are predominantly the result of infestation by invasive dreissenid mussels and changes in habitat. The species is now considered imperilled across large portions of its distribution, especially in the Laurentian Great Lakes region.
2. The genetic diversity and structure of the remnant populations in the Great Lakes region were assessed using 10 newly developed microsatellite DNA loci for S. nasutus. Understanding the remaining populations can inform future management projects and determine whether the remnant populations have experienced a genetic bottleneck or a founder effect. We hope that this will inform the conservation of other species in regions founded by, and isolated from, a more genetically diverse source population or with disjointed geographical distributions.
3. Focusing on the Great Lakes region, samples (n = 428) from 62 collection sites in 28 water bodies were collected. Across the locations sampled for S. nasutus 11 genetic populations were identified, with significant genetic differentiation among them. The genetic structure of the species was assessed, with genetic similarities among populations compared and with geographical routes of colonization and gene flow evaluated.
4. Initial colonization from the Atlantic coast into Lake Erie and Lake Ontario is evident, followed by colonization events into nearby inland rivers and lakes. Analyses found evidence of inbreeding in all but one population and evidence of past genetic bottlenecks or strong founder effects in all but four populations. This study deepens our understanding of the genetic past and present of this imperilled species, providing conservation suggestions for the future management of the species.

中文翻译：

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大湖流域东部池塘贻贝Sagittunio nasutus的种群结构，遗传多样性和定殖历史

1. 在过去的几十年中，东部的池塘贻贝Sagittunio nasutus（Bivalvia：Unionida）的丰度和分布在下降。下降主要是由于侵入性的杜鹃贻贝侵扰和栖息地的变化。现在，该物种在其分布的大部分区域都受到了威胁，特别是在劳伦山脉大湖地区。
2. 大湖区域剩余种群的遗传多样性和结构使用10新开发的微卫星DNA的基因座为评估S. nasutus。了解其余种群可以为将来的管理项目提供信息，并确定残余种群是否经历了遗传瓶颈或创始人效应。我们希望这将有助于保护其他物种，这些物种是由更多遗传多样性的源种群或分离的地理区域所建立和隔离的。
3. 以大湖地区为重点，从28个水域的62个采集点采集了样本（n = 428）。在纳索氏葡萄球菌的采样位置上，共鉴定出11个遗传种群，其中有显着的遗传分化。评估了物种的遗传结构，比较了种群之间的遗传相似性，并评估了定居和基因流的地理路线。
4. 从大西洋沿岸到伊利湖和安大略湖的最初殖民化是明显的，然后是向附近内陆河流和湖泊的殖民化事件。分析发现，除了一个种群外，其他所有种群都有近亲繁殖的证据，除四个种群外，所有过去种群均存在过遗传瓶颈或强大的创始人效应。这项研究加深了我们对该受害物种的遗传过去和现在的理解，为该物种的未来管理提供了保护建议。