Differences in amphibian and reptile assemblages between vegetation types in the foothills of the Trans-Mexican Volcanic Belt in the state of Michoacan, Mexico

Abstract

This study presents information on the composition, structure and distribution of herpetofaunal assemblages associated to different vegetation types (pine-oak forest [PE], tropical dry forest [SB], Sabal palm (Sabal pumus) groves [SP] and avocado orchards (Persea americana) [HA]) in a region of which the herpetofaunistic knowledge is markedly limited (municipality of Ario de Rosales, Michoacan). This region includes portions of the foothills of the Trans-Mexican Volcanic Belt, and portions of the lowlands of the Río Balsas Basin. Amphibian and reptiles were registered from August 2009 to November 2010. Different vegetation types presented marked variations in herpetofaunal species richness and assemblage composition. Gamma diversity (total landscape diversity) consisted of 54 species (18 amphibians, 17 snakes, 16 lizards, 3 turtles). SB presented the highest alpha diversity (local diversity), followed by SP, HA, and PE. However, alpha diversity was not an important determinant of gamma diversity. Complementarity among vegetation types was high. The high number of species exclusive to each vegetation type suggests that beta diversity had greater influence than alpha diversity on gamma diversity. Differences in species composition and the high number of exclusive species suggest that herpetofaunal species respond strongly to land cover types. Additionally, ~ 70% of herpetofaunal species registered were endemic to México, 39% were included in Mexican red lists and ~ 6% were considered at global risk. The high herpetofaunal species turnover among habitats results in exceptionally high levels of herpetofauna diversity in the studied region.