Amphibian chytrid infections along the highest elevational gradient of the Brazilian Atlantic Forest.

Abstract

Environmental variation along elevational gradients shapes conditions for pathogen development, which influences disease outcomes. Chytridiomycosis is a non-vectored disease caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd) and is responsible for massive declines of amphibian populations all over the world. Several biotic and abiotic factors are known to influence Bd infection dynamics in amphibians, including temperature and host species richness. Here, we quantified Bd prevalence and load along an elevational gradient in the Caparaó National Park (CNP), Brazil, and tested for associations of Bd infections with elevation, temperature, and species richness. We hypothesized that Bd infections would increase as local species richness decreased with elevation. We detected Bd along the entire elevational gradient and found a negative association between infection load and elevation. We did not detect significant associations between infection prevalence and elevation. Our findings are consistent with other wide elevational gradient studies, but are contrary to 2 other studies performed in the Atlantic Forest. We did not find the minimum elevational range that should be sampled to detect the influence of elevation on Bd variation. Our study represents the widest elevational gradient that has been sampled in Brazil and contributes to a better understanding of Bd distribution and dynamics in natural systems.