Unveiling the Role of Elevation on the Diversity and Distribution of Mountain Frogs in the Brazilian Semiarid

Montane ecosystems serve as natural laboratories for understanding and monitoring the current and future impacts of climate change. However, the mechanisms underlying biodiversity patterns in these environments remain poorly understood. We investigated how elevation and aquatic system influence anuran richness, abundance, and species turnover among three mountains in the semiarid Caatinga of Ceará State, Brazil. We also tested whether species' optimal elevations are related to their range-size distributions. We conducted field surveys at 27 sites during the rainy season (February–May 2019). We used linear mixed models to assess the effects of elevation and aquatic system on anuran assemblages, including mountain identity as a random factor to account for site-specific variation. To test Rapoport's rule, we applied non-parametric Kernel regression. Elevation significantly affected only species turnover, whereas the aquatic system influenced richness, abundance, and turnover. Although Rapoport's rule was not supported, species with optimal elevations at both low and high elevations exhibited narrow range sizes. Identifying the main drivers of anuran diversity and distribution in montane environments is crucial for understanding ecological patterns, processes, and the potential impacts of environmental change.