Pre-Miocene evolutionary dynamics of tropical rainforests from a dated phylogeny of the palm family

Tropical rainforests (TRFs) are the most species-rich terrestrial biome on Earth, which experienced a series of global climate fluctuations since the mid-Cretaceous. However, the relationship between the evolutionary dynamics of TRFs and global climate changes is poorly understood. As an important element of the TRF biome, the palm family Arecaceae provides an ideal model to study the evolutionary history of TRFs. We present a new palm phylogeny based on combined next-generation and Sanger sequence data, covering 181/184 genera and 604 of the 2500 accepted species, and calibrated it with 12 fossils to infer the pre-Miocene temporal evolutionary dynamics of the family. Results show that Arecaceae started to diversify at c. 108.3 million years ago (Ma) during the mid-Cretaceous, and the diversification rate of the family generally increased during global warming periods and decreased during cooling periods from the mid-Cretaceous to the end of the Oligocene. The extinction rate of palms increased lastingly since the Oligocene when global temperature was relatively low. Our data for palms in combination with those from other taxa suggest that marked species turnover might have occurred in the accumulation of species diversity of TRFs during different geological eras under the context of global climate changes.