Application of the quadratic entropy indices for diversity studies of drosophilid assemblages

Abstract

Most diversity indices widely used in ecology (e.g. the Shannon-Wiener index and the Gini-Simpson index) do not reflect taxonomic or other differences among species. Quadratic entropy, proposed by C.R. Rao (1982), takes these differences into account. The aim of this paper is to demonstrate the application of this diversity index in investigations of drosophilid species diversity. Quadratic entropy and Simpson index values are also compared. The elements of the difference matrix in the quadratic form are taxonomic differences (distances) among the species. The difference is defined by the position of the lowest-ranking taxon containing both species. According to the results, the Gini-Simpson index and the taxonomic quadratic entropy are positively correlated. The observed differences are due to the fact that assemblages with greater taxonomic distances produce greater quadratic entropy. Drosophilid species can be assigned to specific life habit classes, more specifically to resource types. After postulating differences between the types, we used the quadratic entropy measure to analyse resource diversity. These kinds of examinations approximate to an operative association of species diversity and environmental diversity.