1. Plots of local versus regional species richness are an exciting new tool for testing for
species saturation in ecological communities. In this method, the local richness of a
community is plotted as a function of its regional richness for different biogeographical
regions. A proportional relationship between local and regional richness is interpreted as
evidence for an unsaturated community, that is, a community with strong evolutionary limits
to local richness. There will be no correlation between local and regional richness in a …