Interactions between environmental variability and immigration rate control patterns of species diversity

That immigration can change the impact of the frequency of the environmental variation on diversity from monotonically decreasing to unimodal (IDH type) pattern emphasizes that the regional process can be important for explanations of the diversity patterns, especially when the immigration rates are uncorrelated to the local conditions. The strong interactions between community properties, immigration rate, and the spectrum of environmental variation suggest that small changes in community properties or in dispersal rates can have a large impact on species diversity.