Potential effects of climate change on a Neotropical frog genus: changes in the spatial diversity patterns of Leptodactylus (Anura, Leptodactylidae) and implications for their conservation

摘要

Climate change and habitat loss are key threats to biodiversity, by acting as controlling factors of species' distributions. In this study, we combined ecological niche modeling with an innovative range-diversity analysis, which simultaneously addresses geographical ranges and species richness, to describe current biodiversity distribution patterns of Leptodactylus frogs, and to evaluate their expected changes under climate change scenarios. The genus Leptodactylus is distributed across 13.4 million km(2) from Mexico to central Argentina, with overall good-quality presence records and a robust phylogeny. The highest species richness occurred in the Amazonian Forests of Bolivia and Peru, while the lowest species richness was observed in the latitudinal limits of the genus distribution. The range sizes of individual species exhibited a unimodal frequency pattern, with many small ranges and few large ranges. The dispersion field allowed us to identify the Caatinga as a "coldspot," i.e., a site with few species of restricted range size, and the moist forest from Bolivia as a site with many species of medium-size ranges. Under climate change, we expect to observe a general decrease and a geographic displacement of the specific range sizes, but no species extinctions. These patterns imply a decrease in local species richness, which contrasts with a regional increase of biotic heterogeneity.