Modelling phylogenetic diversity

The paper proposes a model for measuring and valuing biodiversity based on evolutionary information, called the phylogenetic tree model. While avoiding the strong restrictions of Weitzman’s [Quart. J. Econ. 107 (1992) 363] “cladistic” approach, the phylogenetic tree model retains much of the mathematical simplicity of the cladistic model. In particular, in the phylogenetic tree model the diversity of any set of species can be recursively determined from the pairwise dissimilarities between them. The restrictions imposed by the phylogenetic tree model on the underlying dissimilarity metric are characterized and shown to be weaker than those entailed by the cladistic model. An especially parsimonous version of the phylogenetic tree model is obtained by invoking an appropriate notion of translation invariance.