An autoregressive model for global vertebrate richness rankings: long-distance dispersers may have stronger spatial structures

Abstract

BackgroundSpatial autocorrelations are one of the most prevalent natural phenomena in ecological data. It is generally assumed that short-distance dispersers are spatially limited and thus have stronger spatial autocorrelation patterns than do long-distance dispersers. To test this hypothesis, I quantified and compared spatial autocorrelation patterns of global richness rankings of amphibians, mammals, and birds using an autoregressive model. A species richness ranking was used as a proxy of species richness, which was obtained through a digital image processing method from published world maps of species richness.ResultsThe results showed that the spatial structure could explain the highest variance involved in global richness rankings of mammals (intermediate-distance dispersers), followed by birds (long-distance dispersers). In contrast, amphibians, representing short-distance dispersers, had the lowest degree of spatial autocorrelation patterns. Thus, the present results do not support the abovementioned hypothesis.ConclusionsIn conclusion, a complex relationship exists between an animal's dispersal ability and its spatial autocorrelation pattern. The dispersal abilities of species can be negatively correlated with spatial autocorrelation patterns.