Fitting and empirical evaluation of models for species abundance distributions

Identifying and explaining patterns in the commonness and rarity of species has been a fundamental concern of community ecology for nearly a century (Chapter 8). Such species abundance distributions, when considered without reference to species identity, are particularly useful to ecologists for two reasons. Firstly, all assemblages have abundance distributions to compare with one another and, secondly, those distributions contain more information than univariate statistics such as species richness or other diversity metrics (McGill et al. 2007). Consequently, ecologists frequently analyse abundance distributions to identify systematic regularities that hold across disparate assemblages and to test ecological theory that purports to explain such regularities.