Isthmian Central America (ICA) is one of the most biodiverse regions in the world, hosting an exceptionally high number of species per unit area. ICA was formed <25 million years ago and, consequently, its biotic assemblage is relatively young and derived from both colonization and in situ diversification. Despite intensive taxonomic work on the local fauna, the potential forces driving genetic divergences and ultimately speciation in ICA remain poorly studied. Here, we used a landscape genetics approach to test whether isolation by distance, topography, habitat suitability, or environment drive the genetic diversity of the regional frog assemblage. To this end, we combined data on landscape features and mitochondrial DNA sequence variation for nine codistributed amphibian species with disparate life histories. In five species, we found that at least one of the factors tested explained patterns of genetic divergence. However, rather than finding a general pattern, our results revealed idiosyncratic responses to historical and ecological processes, indicating that intrinsic life-history characteristics may determine the effect of different drivers of isolation on genetic divergence in ICA. Our work also suggests that the convergence of several factors promoting isolation among populations over a heterogeneous landscape might maximize genetic differentiation, despite short geographical distances. In conclusion, abiotic factors and geographical features have differentially affected the genetic diversity across the regional frog assemblage. Much more complex models (i.e., considering multiple drivers), beyond simple vicariance of Caribbean and Pacific lineages, are needed to better understand the evolutionary history of ICA's diverse biotas.

中文翻译：

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中美洲地峡复杂景观中对遗传分化驱动因素的特殊反应


中美洲地峡 (ICA) 是世界上生物多样性最丰富的地区之一，每单位面积拥有异常多的物种。 ICA 形成于 2500 万年前，因此，其生物组合相对年轻，并且源自殖民化和原位多样化。尽管对当地动物群进行了大量的分类学工作，但驱动 ICA 遗传差异和最终物种形成的潜在力量仍然很少研究。在这里，我们使用景观遗传学方法来测试距离、地形、栖息地适宜性或环境的隔离是否会驱动区域青蛙组合的遗传多样性。为此，我们结合了九种具有不同生活史的共同分布的两栖动物物种的景观特征和线粒体 DNA 序列变异的数据。在五个物种中，我们发现至少有一个测试因素可以解释遗传分化的模式。然而，我们的结果并没有找到一般模式，而是揭示了对历史和生态过程的特殊反应，这表明内在的生活史特征可能决定不同的隔离驱动因素对 ICA 遗传分化的影响。我们的工作还表明，尽管地理距离很短，但促进异质景观中种群之间隔离的几个因素的融合可能会最大化遗传分化。总之，非生物因素和地理特征对整个区域青蛙群落的遗传多样性产生了不同的影响。为了更好地理解 ICA 多样化生物群的进化历史，除了加勒比和太平洋谱系的简单变异之外，还需要更复杂的模型（即考虑多个驱动因素）。