Studies comparing the distribution of genetic diversity may help revealing connectivity patterns in marine populations, as they allow identifying factors behind genetic population structure and elucidating the relationship between the habitat and resident species. The macrofauna of sandy beaches constitutes an interesting study subject, since it includes species with contrasting life histories and dispersal strategies, with potential implications on connectivity. In this work, COI sequences of three peracaridan species with direct development (the talitrid amphipod Atlantorchestoidea brasiliensis and the cirolanid isopods Excirolana braziliensis and Excirolana armata), and one decapod with planktonic larvae (the hippid mole crab Emerita brasiliensis), were compared in order to evaluate the influence of dispersal and historical processes in the distribution of their genetic diversity in the Uruguayan coast, covering both marine and estuarine beaches located along the Rio de la Plata. The hypothesis that species with similar life histories show similar geographic patterns of genetic diversity did not completely explain the genetic variability observed in these species. The intertidal Emerita brasiliensis and the supralittoral Excirolana braziliensis presented high genetic homogeneity, with evidence of population expansion originated at similar times. This shared pattern of genetic variability could be explained by their tropical origin and recent colonization of the Uruguayan coast. The intertidal Excirolana armata and the supralittoral Atlantorchestoidea brasiliensis presented high variability, although differences between them could be associated with the beach zone they inhabit. The role of salinity affecting connectivity patterns was important in Excirolana armata and Atlantorchestoidea brasiliensis, which showed genetic differentiation between estuarine and oceanic beaches. Results reinforce the concept that the distribution of genetic variability not always reflects contemporary population structure and that it is important to consider the evolutionary history of the species when studying connectivity in sandy beach populations. Finally, the accelerated rates of warming in the region could favor a demographic explosion of Emerita brasiliensis and Excirolana braziliensis, species with tropical affinities, which is coherent with the documented demographic history of both species.

比较遗传多样性分布的研究可能有助于揭示海洋种群的连通性模式，因为它们可以识别遗传种群结构背后的因素，并阐明栖息地与居民物种之间的关系。沙滩上的大型动物群是一个有趣的研究主题，因为它包括具有相反的生活史和扩散策略的物种，可能对连通性产生影响。在这项工作中，三个直接发育的peracaridan物种（滑倒的两栖类Atlantorchestoidea brasiliensis和Cirolanid等足类Excirolana braziliensis和Excirolana armata）的COI序列以及一个带有浮游幼虫（嬉皮mole蟹）的十足动物荣誉退休巴西），以评估传播和历史进程的影响，在他们的遗传多样性在乌拉圭海岸分布，覆盖沿拉普拉塔河位于海洋和河口的海滩进行了比较。具有相似生活史的物种显示出相似的遗传多样性地理格局的假设并不能完全解释这些物种中观察到的遗传变异性。潮间带巴西Emerita和巴西沿海上Excirolana巴西具有高度的遗传同质性，证据表明种群扩展起源于相似的时间。这种共同的遗传变异性模式可以用它们的热带起源和最近在乌拉圭海岸的殖民来解释。潮间带尽管Excirolana armata和巴西上腹Atlantorchestoidea brasiliensis的变异性很高，但是它们之间的差异可能与它们居住的海滩区有关。盐度对连通性​​模式的影响在Excirolana armata和Atlantorchestoidea brasiliensis中很重要，它们显示出河口和海洋海滩之间的遗传分化。结果强化了这样一个概念，即遗传变异性的分布并不总是反映当代种群结构，并且在研究沙滩种群的连通性时，考虑物种的进化历史很重要。最后，该地区升温的加速可能会促进具有热带亲缘性的巴西Emerita brasiliensis和Excirolana braziliensis与记录的两个物种的人口历史记录一致。