Avalanche index: a new measure of biodiversity based on biological heterogeneity of the communities

Abstract

A variety of indices are available to quantify the diversity of biological communities. All these indices assume that biological diversity can be satisfactorily described by two major components viz., the number of species and their relative abundances. These indices treat all species as equivalent and ignore taxonomic, morphological, or any such biological differences among species of a community. However, two biological communities with similar number and frequencies of species could differ, for instance, with respect to the taxonomic diversity of the constituent species. A common opinion among ecologists has been that any measure of biodiversity should incorporate biological differences among species or the heterogeneity of the community as an important component. In this paper we propose a new measure of diversity, the 'Avalanche index', which in addition to species numbers and frequencies, also uses the biological and ecological differences among species comprising a community. The index attempts to integrate, over all possible species combinations, the biological differences among species in proportion to their frequencies in the community. We use this index to measure the biodiversity of a set of samples of dung beetles and discuss its merits and problems compared to other indices that are being widely used.