Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

The historical processes underlying high diversity in tropical biodiversity hotspots like the Western Ghats of Peninsular India remain poorly understood. We sampled bush frogs on 13 massifs across the Western Ghats Escarpment and examined the relative influence of Quaternary glaciations, ecological gradients and geological processes on the spatial patterns of lineage and clade diversification. The results reveal a large in situ radiation (more than 60 lineages), exhibiting geographical structure and clade-level endemism, with two deeply divergent sister clades, North and South, highlighting the biogeographic significance of an ancient valley, the Palghat Gap. A majority of the bush frog sister lineages were isolated on adjacent massifs, and signatures of range stasis provide support for the dominance of geological processes in allopatric speciation. In situ diversification events within the montane zones (more than 1800 m) of the two highest massifs suggest a role for climate-mediated f...对于印度半岛西高止山脉（Western Ghats）这类热带生物多样性热点区域的高物种多样性背后的历史演化进程，迄今尚未得到充分阐明。本研究在西高止山脉陡崖带的13个山地地块（massif）上对灌丛蛙类开展采样，并分析了第四纪冰期、生态梯度与地质作用对支系与演化支（clade）空间分布格局的相对影响。研究结果揭示了一次大规模的原地辐射演化事件，涉及超过60个支系，该事件呈现出清晰的地理结构特征与演化支水平的特有性，同时存在南北两个深度分化的姐妹演化支，凸显了古河谷帕尔加特山口（Palghat Gap）的生物地理学意义。绝大多数灌丛蛙的姐妹支系均分布于相邻的山地地块中，而分布区停滞（range stasis）的分子特征支持了地质作用在异地物种形成（allopatric speciation）过程中占据主导地位的结论。对两座最高山地地块海拔1800米以上山地带内发生的原地分化事件的分析表明，气候介导的[原文未完整译出]发挥了关键作用。