Figure 3.

The increase of phylogenetic diversity (PD) with area in Mediterranean-type ecosystems. The observed PD–area relationship (in orange: circles, data; line, power-law fit) is well approximated by an expectation (eqn 4, in blue) obtained by simple power transformation of the classical species–area relationship (in black: crosses, data; line, power-law fit). The power-law exponent z_PD of the PD–area relationship is well approximated by the product of the power-law exponent of the species–area relationship z and the power-law exponent of the species–PD relationship z*. PD increases with habitat area at a slower pace than species, and the difference is the largest in floras where species are the least phylogenetically distinct (i.e. in the kwongan and fynbos).