Historical biogeography of <i>Vellozia</i> (Velloziaceae) reveals range expansion in South American mountaintops after climatic cooling events and increased diversification rates after the occupation of Southern <i>Espinhaço</i> Province

Abstract The campos rupestres and the Brazilian Atlantic Forest Inselbergs (BAFI) are highly diverse vegetation types that grow on mountaintops of eastern Brazil and show outstanding levels of endemism. The plant family Velloziaceae is an iconic element of these vegetations, with the genus Vellozia, being exceptionally abundant in both these vegetations. In this study, we use Vellozia as a model to address three main questions: (i) What was the distribution of Vellozia’s most recent common ancestor? (ii) Did the range expansions of Vellozia occur during periods characterized by global cooling? (iii) When did Vellozia colonize the different South American highlands they occupy nowadays? To address these questions, we reconstructed the phylogeny of Vellozia using sequences of four molecular markers analysed using Bayesian and maximum likelihood inferences. We used the resulting phylogeny to reconstruct the ancestral distribution of Vellozia using the DEC model. Our findings indicate that Vellozia originated and subsequently diversified in the Oligocene, when the genus was broadly distributed through the Andes, BAFI, Cerrado, Caatinga, and the Chapada Diamantina, suggesting that the Cerrado may acted as a corridor between the Andes and eastern mountaintop vegetations. Vellozia subsequently occupied the southern Espinhaço during the Early Miocene, which was followed by increased diversification rates and several range expansions, especially after the Middle-Miocene Climatic Optimum, when cooler and drier periods allowed the expansion of open environments and the retraction of forests, allowing Vellozia to expand their distribution. These results highlight the unique evolutionary history of Vellozia and the importance of climatic cooling for the expansion of the genus.