Mesoamerican roots: the biogeographic history of the fern genus Pleopeltis

Abstract The genus Pleopeltis stands out for its high species richness in tropical montane regions and its disjunct neotropical–afrotropical distribution, with most species occurring in the Neotropics. This distribution provides a unique opportunity to explore dispersal patterns, a key mechanism in fern biogeography. In this study, we aimed to identify the biogeographic processes shaping the distribution of Pleopeltis and the directionality of its dispersal events throughout evolutionary history. We analysed a combined dataset of three plastid regions from 70 species to infer divergence times. Ancestral range estimation and stochastic biogeographic mapping were used to elucidate biogeographic patterns and processes. Our findings showed that dispersal was the main process driving the genus’s distribution, accounting for nearly half of the inferred biogeographic events. Notably, we identified a recent west-to-east dispersal pattern connecting the Neotropics with the Paleotropics, highlighting the significance of long-distance dispersal in ferns. Mexico and Central America were identified as the centre of origin and diversity for the genus and the main source of dispersal. The Andes were the second most important centre, functioning as a source and sink for dispersal events. These findings emphasize the critical roles of these dynamic centres in the diversification and distribution of global biodiversity.