The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
BMC Evol Biol. 2019 Feb 1;19(1):41. doi: 10.1186/s12862-019-1367-6.
Understanding the relative influence of vicariance and dispersal in shaping Old World tropical biodiversity remains a challenge. We aimed to infer the roles of these alternative biogeographic processes using a species time-tree for the centipede genus Ethmostigmus from the Old World tropics. Additionally, we explored fine-scale biogeographic patterns for an endemic radiation of Ethmostigmus from the peninsular Indian Plate (PIP), an area with complex geological and climatic history.
Divergence time estimates suggest that Ethmostigmus began diversifying in the Late Cretaceous, 99 (± 25) million years ago (Ma), its early biogeographic history shaped by vicariance. Members of Ethmostigmus in PIP form a monophyletic group that underwent endemic radiation in the Late Cretaceous, 72 (± 25) Ma. In contrast, a new species of Ethmostigmus from north-east India formed a clade with African/Australian species. Fine-scale biogeographic analyses in PIP predict that Indian Ethmostigmus had an ancestor in southern-central parts of the Western Ghats. This was followed by four independent dispersal events from the southern-central Western Ghats to the Eastern Ghats, and between different parts of the Western Ghats in the Cenozoic.
Our results are consistent with Gondwanan break-up driving the early evolutionary history of the genus Ethmostigmus. Multiple dispersal events coinciding with geo-climatic events throughout the Cenozoic shaped diversification in PIP. Ethmostigmus species in PIP are restricted to wet forests and have retained that niche throughout their diversification.
了解分异和扩散在塑造旧世界热带生物多样性方面的相对影响仍然是一个挑战。我们的目的是使用旧世界热带蜈蚣属 Ethmostigmus 的物种时间树来推断这些替代生物地理过程的作用。此外，我们还探索了来自印度半岛（PIP）的 Ethmostigmus 特有辐射的精细生物地理格局，该地区具有复杂的地质和气候历史。
分歧时间估计表明，Ethmostigmus 起源于白垩纪晚期，距今约 9900 万年（Ma），其早期的生物地理历史由分异形成。PIP 中的 Ethmostigmus 成员形成一个单系群，在白垩纪晚期经历了特有辐射，距今约 7200 万年（Ma）。相比之下，来自印度东北部的一个 Ethmostigmus 新种与非洲/澳大利亚的物种形成一个分支。PIP 中的精细生物地理分析预测，印度 Ethmostigmus 的祖先是在西高止山脉的中南部。随后发生了四次独立的扩散事件，从西高止山脉的中南部到东高止山脉，以及在新生代期间西高止山脉的不同部分之间。
我们的结果与冈瓦纳大陆分裂驱动 Ethmostigmus 属的早期进化历史一致。与新生代期间的地理气候事件相吻合的多次扩散事件塑造了 PIP 的多样化。PIP 中的 Ethmostigmus 物种仅限于湿润森林，并在其多样化过程中保留了这一生态位。
