Precipitation is the main axis of tropical plant phylogenetic turnover across space and time

Early natural historians – Comte de Buffon, von Humboldt and De Candolle – established ecology and geography as two principal axes determining the distribution of groups of organisms, laying the foundations for biogeography over the subsequent 200 years, yet the relative importance of these two axes remains unresolved. Leveraging phylogenomic and global species distribution data for Mimosoid legumes, an iconic pantropical clade with 3,400 species, we show that the water availability gradient from deserts to rainforests dictates turnover of lineages within continents across the tropics. We demonstrate that 95% of speciation occurs within a precipitation niche, showing profound phylogenetic niche conservatism, and that lineage turnover boundaries coincide with isohyets of precipitation. We reveal similar patterns on different continents, implying that evolution and dispersal follow universal processes. Authors: Jens J. Ringelberg, Erik J.M. Koenen, Benjamin Sauter, Anahita Aebli, Juliana G. Rando, João R. Iganci, Luciano P. de Queiroz, Daniel J. Murphy, Myriam Gaudeul, Anne Bruneau, Melissa Luckow, Gwilym P. Lewis, Joseph T. Miller, Marcelo F. Simon, Lucas S.B. Jordão, Matías Morales, C. Donovan Bailey, Madhugiri Nageswara-Rao, Oriane Loiseau, R. Toby Pennington, Kyle G. Dexter, Niklaus E. Zimmermann & Colin E. Hughes