THE PHYLOGENETIC MOMENT - A NEW DIVERSITY MEASURE, WITH PROCEDURES FOR MEASUREMENT AND OPTIMIZATION

The measurement of diversity in biological systems is an increasingly important requirement in environmental planning at regional, national, and even international levels. Phylogenetic diversity indicates the b iological variety present in a set of species by reference to the phyl ogenetic relationships amongst the species. A new diversity measure is proposed which for a given group indicates how well a given set of ex tant taxa represent the group as a whole. The new measure is called th e phylogenetic moment, and is related to the p-median definition of lo cational efficiency in location-allocation analysis. Several analytica l techniques for the new measure are described: an evaluation procedur e, an heuristic optimisation procedure designed to select a representa tionally efficient set of taxa, and an exact algorithm for the special case where only one taxon is to be selected. The authors describe the application of the procedures in conservation planning for Australian bat fauna, and report the results of performance tests on a variety o f other data sets. Because of their efficient performance and modest s torage requirements, the procedures are well suited to the analysis of large taxonomic trees.