Figure 1.

Conceptual figure illustrating, under the random community assembly model, the expected effect of phylogenetic tree shape on the relationship between (a) phylogenetic diversity (PD) and species richness, (b) PD and habitat area and (c) phylogenetic similarity and geographic distance. Here the PD of a set of species is measured as the phylogenetic branch-length joining all species in the set to the root. Star-like phylogenetic trees (with high distinctiveness, in orange) are characterized by steep species–PD curves (slope z* ∼ 1). Phylogenies with decreasing distinctiveness (in blue) have shallower species–PD curves, resulting in shallower PD–area curves, and shallower phylogenetic distance–decay curves.