Data from: Early diversification trend and Asian origin for extant bat lineages

Bats are a unique mammalian group, which belong to one of the largest and most diverse mammalian radiations, but their early diversification is still poorly understood, and conflicting hypotheses have emerged regarding their biogeographic history. Understanding their diversification is crucial for untangling the enigmatic evolutionary history of bats. In this study, we elucidated the rate of diversification and the biogeographic history of extant bat lineages using genus-level chronograms. The results suggest that a rapid adaptive radiation persisted from the emergence of crown bats until the Early Eocene Climatic Optimum, whereas there was a major deceleration in diversification around 35–49 Ma. There was a positive association between changes in the palaeotemperature and the net diversification rate until 35 Ma, which suggests that the palaeotemperature may have played an important role in the regulation of ecological opportunities. By contrast, there were unexpectedly higher diversification rates around 25–35 Ma during a period characterized by intense and long-lasting global cooling, which implies that intrinsic innovations or adaptations may have released some lineages from the intense selective pressures associated with these severe conditions. Our reconstruction of the ancestral distribution suggests an Asian origin for bats, thereby indicating that the current panglobal but disjunct distribution pattern of extant bats may be related to events involving seriate cross-continental dispersal and local extinction, as well as the influence of geological events and the expansion and contraction of megathermal rainforests during the Tertiary.

蝙蝠是一类独特的哺乳动物类群，隶属于哺乳动物辐射演化中规模最大、多样性最丰富的类群之一，但其早期多样化进程至今仍未被充分认知，学界围绕其生物地理历史（biogeographic history）也提出了诸多相互矛盾的假说。厘清蝙蝠的多样化历程，对于解开其神秘的演化历史谜团至关重要。本研究借助属水平时间树（genus-level chronograms），阐明了现生蝙蝠支系的多样化速率与生物地理历史。研究结果显示：从冠群蝙蝠（crown bats）出现直至始新世早期气候最适宜期（Early Eocene Climatic Optimum），持续存在快速的适应性辐射；而在约3500万至4900万年前，蝙蝠的多样化速率出现了显著减缓。在约3500万年前之前，古温度变化与净多样化速率（net diversification rate）呈正相关关系，这表明古温度可能在调控生态机遇方面发挥了关键作用。与之形成鲜明反差的是，在约2500万至3500万年前这段以强烈且持久的全球降温为特征的时期，蝙蝠的多样化速率却意外升高，这暗示内在创新或适应性演化或许帮助部分支系摆脱了极端气候条件带来的强烈选择压力。我们对祖先分布区的重建结果表明，蝙蝠起源于亚洲，这意味着现生蝙蝠当前全球分布但呈间断状的格局，可能与一系列跨大陆扩散事件、局部灭绝事件，以及第三纪（Tertiary）期间的地质活动和热带雨林的扩张与收缩密切相关。