"Modelagem e adequabilidade climática do clado ereta de Oxypetalum (Asclepiadoideae, Apocynaceae). "

Abstract

Oxypetalum is a Neotropical genus of the Apocynaceae family that has a well-resolved phylogeny but few biogeographic studies. We selected a clade with nine erect species of Oxypetalum, from a previously published phylogeny, with the aim of analyzing its distribution and climatic suitability in the present and in future projections under climate change, through predictive modeling. The geographic data were obtained from digital platforms and curated to order to eliminate doubtful records, duplicates and centroids. The study area was defined as the total area surrounding the occurrence points. The data were organized in a matrix to create models for the present and the future. Subsequently, the models were combined with maps of vegetation remnants to identify areas accessible to the species in the future. Our results showed that the clade occurs mainly in the Cerrado, extending to Bolivia, central Argentina and Uruguay. However, the greatest climatic suitability observed for the present is in the southern region of Brazil, extending into southern Paraguay, eastern Argentina, and Uruguay. In the future, the entire Cerrado region becomes climatically suitable for the erect clade. Specific areas are limited to southern Brazil, including much of Santa Catarina, eastern Paraná and Rio Grande do Sul. By combining the climatic suitability maps with remaining vegetation, we found that accessible areas are restricted to high-altitude regions in eastern Paraná and southern Santa Catarina. Remnant areas persist mainly in Rio Grande do Sul. We conclude that, despite the preference of the erect clade for warmer and drier environments, the increase in extreme heat and drought events caused by climate change will forces the clade to seek more humid areas in the future, in search of climatic stability.