The role of environmental heterogeneity in the diversity of the amphibian fauna of the Transmexican Volcanic Belt

Mexico’s complex topography, variety of climates, geological history, and geographic position combine to produce heterogeneity in the amphibian fauna of biogeographic regions such as the Transmexican Volcanic Belt (TVB), a physiographic province with a semi-warm western region and a temperate eastern region. Richness, endemicity, and phylobetadiversity patterns of amphibian communities in the TVB were evaluated using different grid-cell sizes. A total of 143 species in 36 genera were studied. Species richness was higher in the eastern region than in the western region. Endemicity and phyloendemicity values were low, except in a few cells in the eastern region. The amphibian communities in the TVB comprise distinct assemblages, and biotic interactions are the primary drivers of community structure. Taxonomic and phylogenetic beta diversity indices were correlated with geographic distance, and differences in precipitation seasonality between the Last Glacial Maximum (LGM) and current conditions, as well as soil temperature, were the main factors explaining species turnover. The study results confirm that environmental heterogeneity promotes high levels of taxonomic and phylogenetic diversity among the Mexican amphibian fauna. These findings may be useful in future management and conservation efforts.