Data from: Multiple Quaternary refugia in the eastern Guiana Shield revealed by comparative phylogeography of 12 frog species

The Guiana Shield is one of the most pristine regions of Amazonia and biologically one of the richest areas on Earth. How and when the massive diversity of life that exists in Amazonia arose remains the subject of considerable debate. The prevailing hypothesis of Quaternary glacial refugia suggests that a part of the eastern Guiana Shield, among other areas in Amazonia, served as stable, forested refugia during periods of aridity. However, the recently proposed Disturbance-Vicariance hypothesis proposes that fluctuations in temperature on orbital timescales, with some associated aridity, have driven Neotropical diversification. The expectations of the temporal and spatial organization of biodiversity differ between these two hypotheses. Here, we compare the genetic structure of 12 leaf-litter inhabiting frog species from the Guiana Shield lowlands using a combination of mitochondrial and nuclear sequence in an integrative analytical approach that includes phylogenetic reconstructions, molecular dating, and Geographic Information System methods. This comparative and integrated approach overcomes the well-known limitations of phylogeographic inference based on single species and single loci. All of the focal species exhibit distinct phylogeographic patterns highlighting taxon specific historical distributions, ecological tolerances to climatic disturbance and dispersal abilities. Nevertheless, all but one species exhibit a history of fragmentation/isolation within the eastern Guiana Shield during the Quaternary with spatial and temporal concordance among species. The signature of isolation in northern French Guiana during the early Pleistocene is particularly clear. The simultaneity of the divergence between Northern French Guiana and other Guiana Shield lineages is supported by Approximate Bayesian Computation. Sub-structure observed throughout the Guiana Shield suggests further Quaternary fragmentation and a role for rivers. Our findings support fragmentation of moist tropical forest in the eastern Guiana Shield during this period when the Refuge Hypothesis would have the region serving as a contiguous wet-forest refuge.

圭亚那地盾（Guiana Shield）是亚马孙流域最原始的区域之一，同时也是地球上生物多样性最为丰富的区域之一。亚马孙流域现存的海量生命多样性究竟如何形成、何时形成，至今仍是学界广泛争论的议题。主流的第四纪冰期避难所假说（Quaternary glacial refugia）提出，包括圭亚那地盾东部在内的部分亚马孙区域，在干旱时期曾作为稳定的森林避难所存续。然而新近提出的扰动-分化假说（Disturbance-Vicariance hypothesis）则认为，轨道尺度的温度波动伴随一定程度的干旱，推动了新热带区的生物多样化进程。这两种假说对生物多样性的时空组织模式有着截然不同的预期。本研究结合线粒体序列与核序列，采用涵盖系统发育重建、分子年代测定以及地理信息系统（Geographic Information System）方法的整合分析框架，对圭亚那低地栖息于落叶层的12种蛙类的遗传结构开展了比较研究。这种整合式的比较研究方法，克服了以往基于单一物种、单一位点的系统发生生物地理学推断所存在的公认局限。所有目标物种均呈现出独特的系统发生生物地理学模式，体现出类群特异性的历史分布格局、对气候扰动的生态耐受能力以及扩散能力差异。尽管如此，除一个物种外，其余所有物种均显示出第四纪时期圭亚那地盾东部发生种群分化与隔离的历史特征，且不同物种间的分化在空间与时间上具有一致性。早更新世时期法属圭亚那北部的种群隔离信号尤为显著。法属圭亚那北部类群与其他圭亚那地盾支系间的分化同步性，得到了近似贝叶斯计算（Approximate Bayesian Computation）分析的支持。圭亚那地盾全域观测到的亚结构，暗示第四纪时期存在进一步的种群片段化，且河流在此过程中发挥了一定作用。本研究结果表明，在第四纪冰期避难所假说认为该区域应作为连续湿润森林避难所存在的时期，圭亚那地盾东部的湿润热带森林反而发生了片段化。