Global meta-analysis of elevational diversity for amphibians and reptiles

A global meta-analysis was used to elucidate a mechanistic understanding of elevational species richness of amphibians and reptiles by examining climatic factors, spatial constraints, latitude, and regional history. Salamanders, frogs, and snakes were also examined individually. The analyses were conducted using 90 well-sampled studies from a total of 165 elevational gradients of herpetofauna species richness from Old and New World Mountains spanning 36.5° S to 49.5° N latitude. There was support for several elevational richness patterns. The majority of reptiles demonstrated decreasing species richness with increasing elevation, but a substantial portion exhibited either high species richness across the lower elevations (low elevation plateau) or mid-elevation peaks in species richness. Amphibians exhibited decreasing, low elevation plateaus, and mid-elevation peaks in species richness in similar quantity across the data sets, with a few studies finding increasing or bimodal richness patterns. Tests of spatial constraints show low concordance with null model predictions. Trends in elevational richness appear to be only weakly related climate and do not strongly support the elevational climate model. Latitudinal trends in richness with elevation for particular groups suggest support for niche conservatism.