Biogeography and evolution of the pantropical rainforest genus <i>Crudia</i> (Leguminosae, Detarioideae)

Abstract Studies of widespread and disjunct pantropical lineages are crucial for understanding past biogeographic relationships and evaluating whether the seemingly homogeneous tropical environments that these lineages inhabit is related to convergent evolution of characteristics that allow occupancy of these habitats or from a single ancestral habitat that subsequently diversified. Here, we investigate the systematics and biogeography of the pantropical genus Crudia (Leguminosae, Detarioideae) using five nuclear markers (ETS, ITS/5.8S, AGT1, AIGP, CALTL) and a broad taxonomic and geographic species sampling. Our Bayesian inference phylogenetic analysis supports Crudia as monophyletic and reveals a strong geographic structure with a clade of Asian species sister to a clade composed of African and American lineages, the latter forming a monophyletic group. Relationships among species within each clade remain mostly unresolved, particularly in the Asian clade. The analyses show that some morphospecies are congruent with clades recovered using molecular markers, whereas others may need further investigation to properly define species limits. Biogeographical and divergence time analyses show that Crudia first evolved during the Eocene from an African ancestor, and subsequently migrated independently to South America and Southeastern Asia. We propose two hypotheses to explain the observed pattern, ranging from oceanic long-distance dispersal, to terrestrial boreotropics expansion, related with the idea of niche conservatism applied to Crudia species, which grow in similar tropical flooded forest habitats across the world.