Spatial patterns in species richness and the geometric constraint simulation model: a global analysis of mid-domain effect in Falconiformes

摘要

Recently, the hypothesis that the geographic distribution of species could be influenced by the shape of the domains' edge, the so-called mid-domain effect (MDE), was included as one of the five credible hypotheses for the spatial gradients in species richness, despite the controversy surrounding its validity. To evaluate the MDE at global scale, we simulated the random placement of the ranges of the species of Falconiformes worldwide, comparing predicted and observed species richness, calculated for the entire species pool or based on species with small, medium and large geographic ranges. Richness was also correlated with broad-scale net primary productivity estimates (NPP-a surrogate variable expressing the effect of available energy). Our tests showed that MDE is not a good predictor of species richness at a global scale, with maximum explanation power around 14%, and that other hypotheses based on history and climate should be invocated to explain these patterns. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved. [References: 33]