Data from: Genomic signatures of paleodrainages in a freshwater fish along the southeastern coast of Brazil: genetic structure reflects past riverine properties

Past shifts in connectivity in riverine environments (e.g., sea level changes) and the properties of current drainages can act as drivers of genetic structure and demographic processes in riverine population of fishes. However, it’s unclear whether the same river properties that structure variation on recent time scales will also leave similar genomic signatures that reflect paleodrainage properties. By characterizing genetic structure in a freshwater fish species (Hollandichthys multifasciatus) from a system of basins along the Atlantic coast of Brazil we test for the effects of paleodrainages caused by sea-level changes during the Pleistocene. Given that the paleodrainage properties differ along the Brazilian coast, we also evaluate if estimated genetic diversity within paleodrainages can be explained by past riverine properties (i.e., area and number of rivers in a paleodrainage). Our results demonstrate that genetic structure between populations is not just highly concordant with paleodrainages, but that differences in the genetic diversity among paleodrainages correspond to the joint effect of differences in the area encompassed by, and the number of rivers, within a paleodrainage. Our findings extend the influence of current riverine properties on genetic diversity to those associated with past paleodrainage properties. We discuss how these findings may explain the inconsistent support for paleodrainages in structuring divergence from different global regions and the importance of taking into account past conditions for understanding the high species diversity of freshwater fish that we currently observe in the world, and especially in the Neotropics.河流生态系统中过往的连通性变化（如海平面变动）与当前流域的属性，可作为鱼类河流种群遗传结构与种群动态过程的驱动因子。然而，目前尚不明确，在近期时间尺度上塑造种群变异的同类河流属性，是否也会留下类似的基因组特征，以反映古流域的属性。本研究针对巴西大西洋沿岸流域系统中的淡水鱼类物种——多带荷兰鱼（Hollandichthys multifasciatus）的遗传结构进行表征，以此检验更新世时期海平面变化所引发的古流域的影响。鉴于巴西沿岸各古流域的属性存在差异，我们还进一步评估了古流域内的估算遗传多样性，是否可通过过往河流属性（即古流域的面积与流域内河流数量）进行解释。研究结果显示，种群间的遗传结构不仅与古流域高度吻合，且古流域间的遗传多样性差异，对应着古流域所涵盖的面积差异与流域内河流数量差异的联合效应。本研究发现将当前河流属性对遗传多样性的影响，拓展至与过往古流域属性相关的范畴。我们进一步讨论了，这些发现如何解释全球不同区域中古流域对种群分化的支持证据不一致的现象，以及考虑过往环境条件，对于理解当前全球（尤其是新热带区）所观测到的淡水鱼类高物种多样性的重要意义。