Climate Change Implications on the Potential Distribution Ranges of Direct-Development Anurans (Brachycephalidae) in the Brazilian Atlantic Forest

Climate change is a major threat to biodiversity due to its deep impact from individuals to ecosystems. Direct-development amphibians, such as the family Brachycephalidae in the Atlantic Forest, are especially vulnerable because they rely on moist microhabitats in the leaf-litter for egg development. Here, we make use of predictive tools to estimate the climate-driven impacts on different geographic distribution parameters of Brachycephalidae anurans. Specifically, we built ecological niche models for 34 out of the 81 species in the family using four algorithms and projected the climatic niche of each species on baseline and 2050 climate change scenarios, separately for two CO₂ emission scenarios (RCP2.6 and RCP8.5). Thus, we were able to compare the size, range shift directions, and richness gradients among the predictions from different time slices. Out of the 34 studied species, 67.6% to 73.5% of the Brachycephalidae species (23–25 species, depending on the CO₂ emission scenario) are predicted to have decreased ranges. Among them, 12 species (~35% of the total species) are predicted to have no climatically suitable area by 2050. On the other hand, 26.5% to 32.4% of the species (nine and 11 species, depending on the CO₂ emission scenario) are projected to increase their climatically suitable areas by 2050. Regarding the central point of the predicted ranges, the mean distance between the baseline and 2050 predictions is 233–237 km (RCP2.6 and RCP8.5, respectively), yet this average is highly variable (±189.1 km/RCP2.6; ±194 km/RCP8.5). Our results also reveal a major loss in Brachycephalidae species richness along the Atlantic coast, whereas a gain in species richness is expected in inland areas of the Atlantic Forest.