Clade-specific consequences of climate change to amphibians in Atlantic Forest protected areas

Background/Question/Methods

The rapid global decline of amphibian population is alarming because many occur for apparently unknown or enigmatic reasons, even inside protected areas (PAs). Some studies have predicted the effects of climate change on amphibians’ distribution and extinction, but the relationship and consequences of climate change to the phylogenetic structure of amphibian assemblages remain obscure. Here, we evaluated how climate change will affect the geographical pattern of amphibian species richness and phylogenetic diversity in PAs along the Atlantic Forest Biodiversity Hotspot in eastern Brazil. We also analyzed how climate change will alter the phylogenetic structure of amphibian assemblages inside PAs and which clades are being favored or hindered with changes in climate. We rasterized digital range maps of 431 amphibian species onto a grid. From these, we obtained a presence-absence matrix that we used to model the present and future distribution of amphibians. We used an ensemble forecasting approach considering the AR4 scenario of the IPCC predicting the climate by 2080 to model species distribution in the future. We built a supertree for amphibians occurring inside PAs by pruning the largest phylogeny available for amphibians. We obtained the phylogenetic composition of 57 amphibian genera using the phylogenetic fuzzy-weighting method.

Results/Conclusions

We found that up to 85% species contracted their ranges and and 12% of species were expected to be regionally extinct. Additionally, such responses were clade specific. Basal clades (e.g., Gymnophiona, Hemiphractidae, and Pipidae) were positively affected by climate change, whereas late-divergent clades (e.g., Cycloramphidae, Centrolenidae, Eleutherodactylidae, Microhylidae) were severely impacted. Also, the distribution of Lithobates catesbeianus, an invasive species in the Atlantic Forest, was favored under climate change. Most PAs would become climatically unsuitable to sustain their current number of species under climate change, leading to a decrease in species richness and diversity. On the other hand, phylogenetic diversity tended to increase given the higher representativeness of basal clades under future climatic conditions. These results suggest that amphibian responses to climate change show a low phylogenetic signal. Families negatively associated with climate change generally have more specialized reproductive modes. On the other hand, the distribution of Pipa, which is restricted to warm regions in the northeastern, could be expanded southwards, increasing the phylogenetic diversity of PAs. A deep analysis of the impacts of climate change not only on species, but also on the evolutionary relationships among species might foster the discussion on clade-level conservation priorities for this imperiled fauna.