Abstract
Tropical rain forest is the most diverse terrestrial biome, yet the drivers of its diversification across space and time remain poorly understood. Although heterogeneous diversification rates, including both ancient and recent radiations, have been reported, these dynamics have rarely been examined within a single lineage across deep evolutionary timescales. Here, we reconstruct a dated phylogenomic tree of the pantropical plant family Annonaceae, sampling 2045 species (∼82% of its diversity) and spanning ∼100 million years of evolutionary history. Diversification dynamics vary markedly across tropical regions, correlated with distinct environmental factors rather than uniform processes. Sea level fluctuations dominate in the Asia-Pacific, whereas paleotemperature shapes diversification in the Afrotropics and Neotropics. We also detect a Late Cretaceous increase in diversification, indicating that a substantial portion of Annonaceae diversity originated before the Cretaceous-Paleogene boundary. Together, these results highlight how regional environmental trajectories have shaped the assembly of a diverse tropical plant family over deep evolutionary time.