Local and regional species diversity in South American Falconiformes: a geostatistical approach

Abstract

The relationship between local and regional diversity in Falconiformes assemblages from South America was estimated. However, species richness was spatially patterned across the continent and this result can bias significance levels of regression analyses. To overcome this problem, we determined the minimum distance between localities that ensures stochastic independence of diversity estimates across space, using geostatistical analyses. Based on the range obtained by a variogram, we analyzed the relationship between local and regional diversity using three regions separated by more than 4800 km. To increase robustness of results, we used 30 different combinations of three regions. Most linear regression slopes between local and regional diversity are significant, but none of the quadratic terms added to test local saturation was significant. This indicates that local assemblages of Falconiformes are unsaturated. Overall, this result indicates the importance of regional and historical processes in the determination of species richness at local scales.