Figure 1. Three simple examples of phylogenetic tree associated to a pair of communities.

Each community is composed of four species. All species are scored as present or absent in each example. All branch lengths are set to one, except for the last example (c) for which species 7 and species 8 display a branch length equal to 0.5. The three examples show similar level of compositional beta diversity (i.e. communities have no species in common) but differ in regards to the level of phylogenetic beta diversity (see main text for more details).