Desiccation resistance explains amphibian distributions in a fragmented tropical forest landscape

Abstract

Context Although amphibian distributions are associated with environmental moisture at global and local scales, less is known about how desiccation tolerance influences landscape distributions of amphibians. Objectives We evaluated two hypotheses linking amphibian distributions in a fragmented tropical forest landscape to desiccation risk. The patch quality hypothesis predicts that desiccation-prone species are absent on small forest patches, which are generally warmer and drier than large patches. Alternatively, the matrix effects hypothesis suggests that desiccationprone species are absent on isolated forest patches surrounded by open savanna because they will be unable to traverse the matrix in which patches occur. Methods We quantified interspecific variation in desiccation proneness using field-based desiccation trials, and tested for associations between desiccation proneness and distributions of amphibians in fragmented forest in northeastern Bolivia. Results Rates of evaporative water loss were negatively associated with an index of dispersal limitation, but unrelated to species’ area requirements. Conclusions By demonstrating that desiccationprone species do not occur on isolated forest patches, we provide clear support for the matrix effects hypothesis. We suggest that desiccation proneness is a key trait that may determine amphibian responses to a range of global change drivers, including habitat loss and fragmentation, invasive species, and climate change.