Amphibian species richness and endemism in tropical montane cloud forests across the Neotropics

Tropical montane cloud forest harbors great species diversity in a small area of the planet and has a high proportion of endemics. At the local scale, species richness is low, but species turnover is high. We examined how amphibian species richness and the number of endemic species varies in cloud forests along a latitudinal gradient (23°N–5°S) in the Neotropics, where the latitudinal distribution of cloud forest is the most widespread compared with all of the other tropical regions. We also compared diversity patterns between anurans, caudates and gymnophionids, and tested their relationship to climate variables. Based on an analysis of 1005 species, we found that amphibian species richness increased towards the equator, but the increase was not linear. In Middle America there is a notable fluctuation in the number of species. The greatest species richness occurred between 6°N and 7°N, and there was an abrupt change between this region and Middle America. Analyses at the level of order and the endemic species level revealed two opposite patterns: anuran, gymnophionid and endemic species richness increased towards lower latitudes, while salamander species richness increased towards northern latitudes. Climate variables explained less than half of the variations in total species richness, suggesting that factors other than climate such as the historical biogeography of each taxon, orographic heterogeneity and the natural history traits of each group may be playing relevant roles in the patterns observed.