ABSTRACT Aim The biodiversity of the Neotropics has been shaped by complex interactions over time with several major geological and climatic events linked to the diversification of lineages. The subtribe Calothecinae (Poaceae) comprises 28 species adapted to open environments, ranging from lowlands to high‐altitude grasslands in America. We aimed to investigate ancestral geographical range shifts, diversification rates and the influence of altitude and anthecia number on the diversification of Calothecinae. Location Neotropics. Taxon Subtribe Calothecinae (Poaceae). Methods We reconstructed a dated phylogeny using data from eight DNA regions for 27 Calothecinae taxa to analyse biogeographic processes, infer diversification rates and assess the influence of altitude and anthecia number per spikelet on the subtribe's diversification. We estimated changes in diversification rates using a Bayesian branch‐specific diversification model implemented in the software RevBayes. Results Calothecinae likely originated during the Miocene, in the Southeastern Brazilian Highlands, after a vicariant event separating it from an Andean clade. Net diversification rates increased at the divergence of the most recent common ancestor of Calothecinae and its sister clade, subtribe Paramochloinae and at the emergence of Poidium within Calothecinae. Ancestral elevation reconstruction suggested that the subtribe originated after a movement from high to mid‐elevations. The best‐fitting model for trait‐dependent diversification indicates that the number of anthecia per spikelet might have influenced the diversification patterns observed across the Calothecinae tree. Main Conclusions We found that Calothecinae originated in the Miocene in the Southeastern Brazilian Highlands, then expanded south‐to‐north across the Americas. Long‐distance dispersal likely facilitated the colonisation of Central America and Mexico. This biogeographic history appears to have been shaped by geological and climatic events, such as the uplift of the Andes and marine transgressions. Additionally, morphological traits, particularly the number of anthecia per spikelet, seem to have played a key role in the group's diversification.
Schröder et al. (Wed,) studied this question.