Criaturas úmidas em um mundo em aquecimento: como as mudanças climáticas afetarão os anuros no semiárido brasileiro?

Abstract

The world has been undergoing a global climate crisis, leading to a substantial increase in the average temperature of the planet. Consequently, amphibians, ectothermic animals that depend on water to survive/reproduce, are facing growing threats. In this study, we compare the influence of climate change on the climatic niche of endemic anuran species from the Caatinga Domain, with restricted occurrence in the Brazilian semi-arid region, versus the climatic niche of congeners with wider distribution. The central hypothesis tested is that climate change will have a more negative impact on species from the semi-arid region than on species with wider distribution. To do so, using ecological niche modeling, we projected potential distribution models and compared two metrics (suitability and extent of occurrence index) between pairs of congenetic species endemic to the Caatinga and those with wider distribution. Suitability indicates the probability of species occurrence in potential distribution models and was calculated for each species as the average suitability of quadrants (55 km x 55 km) with potential species occurrence. The extent of occurrence index indicates the expectation of retraction or expansion of the potential species distribution in future scenarios and was calculated as the area extent (in km2) with suitability greater than 0.7. Occurrence points were obtained from scientific literature, and predictor bioclimatic variables for the models were obtained from WorldClim. The results revealed that the suitability of restricted species from the Caatinga is significantly lower than that of species with wider distribution, across all analyzed time frames. On the other hand, we demonstrated that endemic species tend to expand their distributions in future scenarios, while species with wider distribution maintain their extent of occurrence relatively constant. Our findings suggest that species with wider distribution do not seem to have their distributions substantially affected by climate change, whereas endemic species from the Caatinga would tend to expand their distributions in areas of high suitability and, therefore, be relatively favored by the predicted climate changes over this century.