2025/10/03 by Laura Kragh Frederiksen, Wolf L. Eiserhardt, Hanna Tuomisto
Agricultural and Biological Sciences · Environmental Science · #Ecology and Vegetation Dynamics Studies #Fern and Epiphyte Biology #Plant and animal studies
paper · pdf · doi:10.1002/ecog.08170
openalex publication_date 2025/10/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Understanding how the remarkable biodiversity of the American tropics developed has been a long‐standing question, yet knowledge gaps remain. Previous studies examined the roles of bioregions in shaping diversity patterns but often overlooked speciation, a critical driver of species richness, and insufficiently accounted for temporal changes in speciation and dispersal dynamics. To address this, we investigated the temporal mechanisms of speciation and dispersal that have shaped diversity in the American tropics using ferns (Polypodiopsida) as a model group across nine bioregions. We employed biogeographic stochastic mapping (BSM) and a large‐scale phylogenetic tree alongside extensive occurrence records to infer historical patterns of speciation and dispersal. We find that the American tropics function as a biogeographical maze composed of interconnected corridors, characterised by high emigration and immigration rates, rather than isolated regions. The Andes emerged prominently as a biodiversity radiator, playing a dual role by generating substantial species richness through speciation and acting as a primary source of dispersal to neighbouring regions. This unique position underscores the Andes' pivotal role in structuring fern diversity across the American tropics, contrasting with the Amazonian‐centred patterns typically observed in angiosperms. Our findings highlight the critical importance of considering speciation and historical contexts in relation to changing environments when interpreting patterns of tropical biodiversity.