Seasonal variation in patterns of anuran diversity along a subtropical elevational gradient

Aim: Although many studies have described spatial patterns along elevational gradients, only a handful have investigated their temporal dynamics, which remain poorly understood. Here we investigate patterns of frog spatiotemporal diversity (Anuran: Amphibia) along a subtropical elevational gradient, and assess the importance of temperature in explaining observed patterns. Location: An extensive Brazilian Atlantic Forest elevational gradient ranging from 200 m to 1800 m above sea level. Taxon: Anuran amphibians. Methods: We sampled anurans once each month between September 2017 and August 2018 at 38 ponds along the gradient. We then applied generalized additive models to evaluate the spatiotemporal patterns of anuran diversity (measured as Hill's numbers of order q = 0, 1 and 2) and abundance, and understand the extent to which this variation is explained by ambient temperature. Results: We found seasonal changes in the shape and magnitude of anuran diversity along the elevational gradient. While anuran diversity showed mid-elevation peaks between spring and summer, a low-to-mid elevation plateau was observed during autumn and winter. Abundance peaked at mid-elevations between spring and summer, remained high in the lowlands, and decreased in the highlands between autumn and winter. Overall, anuran diversity and abundance increased from spring to summer but then sharply declined towards winter, showing a nonlinear positive relationship with mean temperature. Temperature accounted for most of the observed spatial and spatiotemporal variation, rather than temporal trends in anuran diversity and abundance. Main Conclusions: Our results suggest that in addition to temperature, other factors such as intrinsic species characteristics may regulate anuran activity patterns throughout the year along the elevational gradient. This study highlights how local anuran diversity is dynamic across the elevational gradient, emphasizing the relevance of considering seasonality to better understand diversity patterns in montane environments, which can be critical to inform conservation strategies.