On properties driving diversity index selection

Abstract: Phylogenies are commonly used to represent the evolutionary relationships between species, and often these phylogenies are equipped with edge lengths that indicate degrees of evolutionary difference. Given such a phylogeny, a popular measure for the biodiversity of a subset of the species is the phylogenetic diversity (PD). But if we want to focus conservation efforts on particular species, we may use a phylogenetic diversity index, a function that shares out the PD value of an entire phylogeny across all of its species. With these indices, various species-level conservation strategies can be evaluated. This work explores how the most suitable diversity indices can be found. In particular, how formalizing the requirement for diversity indices to capture high levels of PD, or to maintain a scoring of taxa in the presence of uncertain edge lengths drives the selection of a suitable index. Furthermore, we provide illustrations of these new mechanisms for diversity index selection in a case study. This analysis includes the comparison to popular phylogenetic indices from the conservation literature.