Figure 2.

Species–phylogenetic diversity (PD) curves in Mediterranean-type ecosystems. The grey circles report, for each value of species richness (S), the PD of 100 communities obtained by randomly sampling S species across the tips of each phylogeny (species–PD relationship). This relationship is well fit by a power law in the four phylogenies (eqn 1, plain grey line). In particular, the power-law fit is much better than the best-fit logarithm (in blue). The intercept of both fits is constrained by the age of the most recent common ancestor, T₀. The species–PD curve corresponding to the combined dataset is also power law, with z* = 0.71 (Figure S3). Coloured data points correspond to actual communities. Orange squares: communities sampled at the 2.5 × 2.5 m scale; black diamonds: communities sampled at the 7.5 × 7.5 m scale; red triangles: communities sampled at the 20 × 20 m scale. Most communities are not significantly different from randomly assembled communities (see Appendix S2 for details).