Elaboration of a function to predict extinctions of toads based on physiological characters

Abstract

Although general patterns of amphibian distribution correspond to those observed for birds and mammals, patterns of endotherm distribution can be highly explained by energetic restrictions. For amphibians, water availability and temperature are the most important factor for species richness distribution. This high association between patterns of amphibian species richness with water availability may be explained by their high skin permeability, which is also an important organ of respiratory gas exchange. To amphibians, dehydration and temperature interact and affect locomotor performance potentially reducing the ability to perform ecologically important behavioral patterns, such as prey capture, escape from predators and sexual partner seek. Global climate changes should affect organisms in all biomes and ecosystems, leading them to two basic paths when phenotypic plasticity is not enough to withstand these changes: dispersal or adaptation. Eventual failure of these paths may lead to demographic collapse and extinction. Amphibians are more globally threatened at 32% than either birds, with 12% of the species, or mammals, with 23% of the species. In this way, studies that provide tools to predict extinction on amphibians populations, based on physiologically relevant variables, are urgently need for this group. Regarding all these aspects this project has two distinct objectives: 1) Use data already collected on preferential temperature, field operative temperature, rates of dehydration in the field, and sensitivity of locomotor performance to dehydration and temperature variation from Brazilian toads to adequate the function of extinction prediction from the application of the method described in Sinervo et al. (2010) for these species; 2) Collect additional data on preferential temperature, field operative temperature, rates of dehydration in the field, and sensitivity of locomotor performance to dehydration and temperature variation from toads that occur in California and estimate the same function developed for Brazilian toads. (AU)