Early diversification trend and Asian origin for extent bat lineages

Area of Science:

• Mammalian evolutionary biology
• Paleoclimatology
• Biogeography

Background:

• Bats represent a highly diverse mammalian radiation, yet their early evolutionary history and biogeographic patterns remain poorly understood.
• Conflicting hypotheses exist regarding the drivers of bat diversification and their global distribution.

Purpose of the Study:

• To elucidate the diversification rates and biogeographic history of extant bat lineages.
• To investigate the influence of paleotemperature and intrinsic adaptations on bat evolutionary trajectories.

Main Methods:

• Analysis of genus-level chronograms to reconstruct evolutionary timelines.
• Reconstruction of ancestral distribution to infer geographic origins.

Main Results:

• A rapid adaptive radiation of bats occurred from their emergence until the Early Eocene Climatic Optimum.
• Diversification decelerated significantly around 35-49 million years ago (Ma), with a positive association between paleotemperature and diversification rates until 35 Ma.
• Unexpectedly high diversification rates were observed between 25-35 Ma during global cooling, suggesting the role of intrinsic adaptations.
• Ancestral distribution reconstruction indicates an Asian origin for bats.

Conclusions:

• Paleotemperature played a significant role in regulating ecological opportunities for bats until 35 Ma.
• Intrinsic adaptations may have enabled some bat lineages to thrive during periods of global cooling.
• The current panglobal distribution of bats is likely a result of continental dispersal, local extinctions, geological events, and rainforest dynamics during the Tertiary.