Life on the edge: a comparative study of eco-physiological adaptations of frogs to tropical semiarid environments

A key goal of ecology and evolution is to understand the relative contributions of environment and history in determining the geographic distribution of organisms. For the Neotropical lowlands, where temperatures are similar across landscapes, we hypothesize that water balance may be a critical but understudied factor in determining the distribution of species. Amphibians are especially sensitive to variation in precipitation due to their permeable skin. Here we focused on lowland frogs of north-western South America and investigated variation among 17 species in potentially important ecologically relevant performance variables related to water balance, and tested for possible adaptations to semiarid conditions within species. We studied frogs from coastal xeric, savannah and wet forest biomes under common laboratory conditions and quantified rates of evaporative water loss, rates of water uptake, and variation in water-searching behavior and performance. We found significant difference...