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会影响物种分布及种群遗传结构。美墨两国境内的里奥格兰德流域（Rio Grande watershed）涵盖了被高强度开发的生态系统，进而导致水生栖息地遭到严重退化。尽管里奥格兰德流域的大规模人为干扰是近期才出现的，但淡水生物的恶劣生存环境很可能在这类干扰发生前就已存在。人为活动与古气候变化的共同作用，或许是塑造里奥格兰德盆地当前水生动物区系分布格局的原因。我们针对分布于里奥格兰德水系（Rio Grande drainage）的濒危淡水蚌类波氏伪前嵴蚌（Popenaias popeii），借助线粒体DNA（mitochondrial DNA）与18个微卫星位点（microsatellite loci）解析其演化历史与种群遗传结构。我们估算了波氏伪前嵴蚌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）推演其在更新世（Pleistocene）时期的演化历史。种群结构分析结果显示，里奥格兰德流域内存在区域性与局域性的种群聚类群。生态位模型预测，在末次冰盛期（last glacial maximum），该物种的适宜栖息地面积发生了大幅缩减。近似贝叶斯计算分析结果表明，该物种的区域性种群结构很可能形成于更新世中晚期，随后新墨西哥州种群在晚更新世经历了种群瓶颈事件。而局域性种群结构则形成于相对较近的时期，其成因可能与人类活动有关。波氏伪前嵴蚌是里奥格兰德盆地本土少数淡水蚌类物种之一，可作为探究地质活动与人为因素如何塑造当前种群遗传结构的典型研究案例。针对该物种的保护策略，应充分考虑其现存种群的碎片化特征。