Projections of suitable habitat loss and its implications in conservation for endemic non-pseudantial Euphorbioideae (Euphorbiaceae) species in Northeastern Brazil under climate change scenarios

Climate change has intensified negative impacts on biodiversity through changes in precipitation patterns and rising global average temperatures. Semi-arid regions, such as parts of Northeastern Brazil, are particularly susceptible to these changes, with projections indicating that they will become hotter and drier, reducing the climatic suitability of several plant species. In this context, endemic and restricted-range species may be highly vulnerable. In this study, we used distribution modeling to estimate potential changes in the geographic distribution and conservation of 12 endemic Euphorbiaceae species from Northeastern Brazil, to inform conservation strategies. We found that climate change will have distinctly different impacts on the suitable habitat areas for the analyzed taxa. Projections indicate that in the optimistic scenario (SSP126), Sapium sceleratum could expand its suitable range by approximately 80%, while Microstachys uleana and Actinostemon appendiculatus will experience limited gains (< 14%), and other species will experience losses exceeding 40%. In the pessimistic scenario (SSP585), five taxa lose areas of suitability above 40%, but Sapium sceleratum and Algernonia bahiensis could expand by 76% and 100%, respectively. We also documented a reduction in species richness in all future climate scenarios analyzed. Furthermore, in both climate scenarios, a general trend toward increasing extinction risk is observed for most species. Thus, this study clearly demonstrates that most endemic species in the family are highly vulnerable to various future climate change scenarios and that conservation measures such as the creation of protected areas within the species' climatically suitable concentrations should be established.