The biogeographic history of a species results from responses to past and current processes, and understanding those responses at both temporal scales is essential. We explored phylogeographic and current genetic variation structure in Ctenomys flamarioni—a subterranean rodent that inhabits a small region of the coastal plain of Brazil—and contrasted the roles of “present-day niche suitability” versus “historical climate stability” to understand current and past intraspecific genetic diversity. We used both mitochondrial DNA sequences (concatenated Cytb and D-loop, n = 78) and nuclear DNA (9 microsatellites loci, n = 154) molecular markers for individuals across the entire distribution of the species. We used phylogeographic trees, Bayesian clustering, and haplotype networks to explore genetic variation and diversity. We correlated genetic diversity with measures of current niche suitability and potential areas of Late Quaternary paleostability. Phylogeographic patterns confirmed low levels of genetic diversity structured at different hierarchical levels. We also found a weak but significant pattern of isolation by distance, indicating that geographical distance partially modulates genetic differences among populations. We also observed a positive correlation between genetic diversity and climate paleostability for microsatellites at local and regional scales. However, we found no significant association between genetic diversity and niche suitability for microsatellites at local or regional scales. We observed several signatures of bottleneck and population expansion at different geographic scales. Our results suggest that Quaternary climatic fluctuations—acting together with habitat suitability and other contemporary factors—played a fundamental role in elucidating the evolutionary history of the species—including patterns of historical dispersal, and current patterns of habitat occupation and genetic structure. In addition, based on our molecular and environmental data sets from the across the range of the species and considering the restricted endemism of C. flamarioni, we emphasize the urgency of conservation actions to protect this endangered species.

中文翻译：

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第四纪气候波动对濒临灭绝的Tuco-tuco-das-dunas（Ctenomys flamarioni）的遗传足迹

一个物种的生物地理历史是对过去和当前过程的反应的结果，并且在两个时间尺度上理解这些反应至关重要。我们探索了 Ctenomys flamarioni（一种栖息在巴西沿海平原小区域的地下啮齿动物）的系统发育地理学和当前遗传变异结构，并将“当前生态位适宜性”与“历史气候稳定性”的作用进行对比，以了解当前和过去的情况种内遗传多样性。我们对整个物种分布中的个体使用了线粒体 DNA 序列（连接的 Cytb 和 D 环，n = 78）和核 DNA（9 个微卫星位点，n = 154）分子标记。我们使用系统发育树、贝叶斯聚类和单倍型网络来探索遗传变异和多样性。我们将遗传多样性与当前生态位适宜性和晚第四纪古稳定的潜在区域的测量相关联。系统发育地理学模式证实了不同层次结构的遗传多样性水平较低。我们还发现了一种微弱但重要的距离隔离模式，表明地理距离部分调节了人群之间的遗传差异。我们还观察到局部和区域尺度的微卫星的遗传多样性与气候古稳定性之间存在正相关性。然而，我们发现遗传多样性与局部或区域尺度的微卫星生态位适宜性之间没有显着关联。我们观察到不同地理范围内瓶颈和人口扩张的几个特征。我们的研究结果表明，第四纪气候波动与栖息地适宜性和其他当代因素共同作用，在阐明物种的进化历史（包括历史扩散模式以及当前栖息地占用模式和遗传结构）方面发挥了基础作用。此外，根据我们整个物种范围的分子和环境数据集，并考虑到 C. flamarioni 的有限特有性，我们强调采取保护行动来保护这一濒危物种的紧迫性。