The distribution, diversity and conservation of the Mexican herpetofauna among its biogeographic provinces

Abstract

Mexico houses a substantial diversity of amphibians and reptiles, with a large number of endemics. We generated a checklist of Mexico’s herpetofauna and their distribution among its biogeographic regions and provinces. We found a total 435 species of amphibians (70.6% endemic to Mexico), and 964 species of reptiles (60.7% endemic to Mexico). The Transition Zone had the greatest herpetofaunal richness, housing 90.8% of the amphibian species and 71.1% of the reptile species that inhabit Mexico. Amphibian and reptile richness decreased from south to north, with the highest richness in the Sierra Madre del Sur, followed by the Trans-volcanic Belt and the Sierra Madre Oriental. According to the IUCN Red List, currently 28.4% of the native species of Mexican amphibians and reptiles are in a category of conservation concern. The Transition Zone, specifically the Sierra Madre del Sur, is of utmost importance due to the conservation status of its species, since this biogeographic province is home to a large number of endemic species. The Neotropical and Nearctic Regions both have around 13% of their species included in some category of conservation concern. The pairwise Jaccard distances among the biogeographic provinces for amphibians and reptiles are highly correlated suggesting parallel patterns of similarity between these two taxonomic groups. We found a positive correlation between Jaccard distances and the length of the shared border between provinces and a negative correlation between Jaccard distance and the distance between the geographic centroids of the provinces, suggesting that geographic proximity plays an important role in the similarity of herpetofauna among biogeographic provinces. The number of species in a province was not correlated with its area or longitude but showed a negative correlation with its latitude. Cluster analyses showed three main clusters of biogeographic provinces for both amphibians and reptiles, with subclusters reflecting geographic proximity and shared habitats. These results highlight the importance of considering geographic factors, such as geographic proximity and habitat similarities, in understanding the distribution and conservation of amphibians and reptiles in Mexico.