is determined by two different things: the mean species diversity at the local level (?) and the differentiation among local sites (?). Other formulations for beta diversity include "absolute species turnover", "Whittaker's species turnover" and "proportional species turnover".

Whittaker proposed several ways of quantifying differentiation, and subsequent generations of ecologists have invented more. As a result, there are now many defined types of beta diversity. Some use beta diversity to refer to any of several indices related to compositional