Data from: Past climate change drives current genetic structure of an endangered freshwater mussel species

Historical-to-recent climate change and anthropogenic disturbance affect species distributions and genetic structure. The Rio Grande watershed of the United States and Mexico encompasses ecosystems that are intensively exploited, resulting in substantial degradation of aquatic habitats. While significant anthropogenic disturbances in the Rio Grande are recent, inhospitable conditions for freshwater organisms likely existed prior to such disturbances. A combination of anthropogenic and past climate factors may contribute to current distributions of aquatic fauna in the Rio Grande basin. We used mitochondrial DNA and 18 microsatellite loci to infer evolutionary history and genetic structure of an endangered freshwater mussel, Popenaias popeii, throughout the Rio Grande drainage. We estimated spatial connectivity and gene flow across extant populations of P. popeii and used ecological niche models (ENMs) and approximate Bayesian computation (ABC) to infer its evolutionary history during the Pleistocene. structure results recovered regional and local population clusters in the Rio Grande. ENMs predicted drastic reductions in suitable habitat during the last glacial maximum. ABC analyses suggested that regional population structure likely arose in this species during the mid-to-late-Pleistocene, and was followed by a late-Pleistocene population bottleneck in New Mexico populations. The local population structure arose relatively recently, perhaps due to anthropogenic factors. Popenaias popeii, one of the few freshwater mussel species native to the Rio Grande basin, is a case study for understanding how both geological and anthropogenic factors shape current population genetic structure. Conservation strategies for this species should account for the fragmented nature of contemporary populations.

从古至今的气候变化与人为干扰，均会影响物种的分布范围与遗传结构。美墨两国境内的格兰德河流域（Rio Grande watershed）涵盖了被高强度开发的生态系统，致使水生栖息地遭到严重退化。尽管格兰德河流域的重大人为干扰发生时间较近，但淡水生物在此类干扰出现之前，就已面临不适宜生存的环境条件。人为活动与古气候变化的共同作用，可能塑造了格兰德河流域当前的水生动物分布格局。我们采用线粒体DNA（mitochondrial DNA）与18个微卫星位点（microsatellite loci），对分布于整个格兰德河水系的濒危淡水蚌——波氏巴蚌（Popenaias popeii）的演化历史与遗传结构进行推演。我们估算了该物种现存种群间的空间连通性与基因流，并借助生态位模型（ecological niche models, ENMs）与近似贝叶斯计算（approximate Bayesian computation, ABC）推演了其在更新世（Pleistocene）时期的演化历史。群体结构分析结果显示，格兰德河流域存在区域性与局域性的种群聚类群。生态位模型预测，在末次盛冰期（last glacial maximum），该物种的适宜栖息地面积大幅缩减。近似贝叶斯计算分析表明，该物种的区域性种群结构大概率形成于中更新世晚期至晚更新世，随后新墨西哥州种群在晚更新世经历了种群瓶颈事件。局域性种群结构的形成时间则相对较近，可能与人为活动相关。波氏巴蚌是格兰德河流域原生的少数淡水蚌物种之一，其可作为研究地质与人为因素如何塑造当前种群遗传结构的案例对象。针对该物种的保护策略，应考虑到其现存种群的碎片化特征。