Fig. 4

Substitution rates in nuclear genes of Epipogium (a) and Hypopitys monotropa (b). The branch lengths denote the number of nucleotide substitutions per position. Branches corresponding to non-photosynthetic species are indicated in red, and those corresponding to photosynthetic species are indicated in green. Branches in which a transition from a photosynthetic to a non-photosynthetic lifestyle occurred are indicated half in green and half in red. Orchis italica and Camellia sinensis, which are employed as outgroups in (a) and (b), respectively, are not shown, since the substitution rate of an outgroup cannot be evaluated