Environmental heterogeneity predicts global species richness patterns better than area

Aim: It is widely accepted that biodiversity can be determined by niche-relate processes and by pure area effects from local to global scales. Their relative importance, however, is still disputed, and empirical tests are still surprisingly scarce at the global scale. We compare the explanatory power of area and environmental heterogeneity as a proxy for niche-related processes as drivers of native mammal species richnessworldwide and with biogeographical regions.

Location: Global

Time Period: Data was collated form the IUCN (2013)

Major Taxa Studied: All mammal species, including possibly extinct species and species with uncertain presence.

Methods: We developed a random walk algorithm to compare the explanatory power of area and environmental heterogeneity on native mammal species richness. As measures for environmental heterogeneity, we used elevation and precipitation ranges, which are well known correlates of species richness.

Results: We find that environmental h...