Climate change and amphibian diversity patterns in Mexico

The aim of this article is to characterize at fine scale alpha and beta diversity patterns for Mexican amphibians and analyze how these patterns might change under a moderate climate-change scenario, highlighting the overall consequences for amphibian diversity at the country level. We used a geo-referenced database gathered from museums worldwide as a basis for climatic envelope models, based on the working assumptions that we can accurately model the ecological niche, niche conservatism, and that the future climate scenario is realistic. We generated six sets of models with different parameters (threshold of presence and dispersal capability) in the modelling processes. We simulated the base line (2000) and future scenarios for Mexican amphibian diversity (2020, 2050, 2080), using climate data layers constructed for Mexico. Using moving-window analyses of different sizes (9, 25, 100, 225 and 400 km(2)) we calculated beta diversity with R.H. Whittaker's formula beta = gamma/alpha(mean). We analyzed the changes of alpha- and beta-diversity spatial patterns during these periods, and performed an analysis of sensitivity for the beta-diversity patterns. We found that setting low dispersal capability generates high levels of species extinctions, but the overall geographic pattern of beta diversity remained stable. Zones of high beta diversity resulted that were associated with topographic formations, while the values of beta diversity initially increased, and then declined over time. Extinctions (complete loss of range within country boundaries) were particularly intense during the period 2020-2050. The results implied that heterogeneous zones associated with mountain ranges will remain particularly important for amphibian diversity and thus constitute areas for continued conservation prioritization in the face of climate change. (C) 2012 Elsevier Ltd. All rights reserved.