Biogeography, ecology and conservation of tropical dry forest herpetofauna of western Mexico

Mexican tropical dry forest in western Mexico, is characterized by a marked seasonality in precipitation, a considerable diversity and high deforestation rates. These forests account for a third of total Mexican herpetofauna species and endemics. I present the results of the analysis of the distribution patterns of reptile and amphibian species in western Mexico. Also presented are the temporal and spatial trends in community structure at local scale using tramping arrays, and the conservation strategies for tropical dry forest herpetofauna, based on the correspondence analysis of distribution patterns of species richness, endemism, endangerment and the analysis of different levels of diversity (alpha, beta and gamma). Both reptile and amphibian species richness varied significantly with latitude, but these patterns are the reflection of the marked gradient of the climatic conditions recorded in this region. Climate favorableness (e.g. temperature) has a positive effect on species richness, whereas, climatic seasonality (e.g. thermal oscillation) has a negative effect. Reptile and amphibian community structure show temporal and spatial trends related to the patterns of environmental seasonality exhibited by tropical dry forest and its associated arroyo forest. These communities were more diverse in arroyo forest and in the rainy season probably due to the greater habitat structure and productivity of this habitat and season. Temporal fluctuations in community structure were more seasonal in amphibians than in reptiles. The protection of tropical dry forest in western Mexico will have a great impact on the efforts to conserve Mexican biodiversity. This region contains a high proportion of the Mexican herpetofauna, including a large number of endemic and endangered species. The substantial correspondence among areas of high species richness, endemism, and endangerment, suggests that several areas along western Mexico should receive conservation priority. Priority should also be given to those regions with high alpha and gamma diversity. Long-term monitoring studies of herpetofauna communities are needed at different sites along western Mexico to assess the conservation status of the species and their populations. It is very important to protect the association of tropical dry forest and arroyo forest to maintain the diversity of reptiles and amphibians in western Mexico.