Fig. 1.—

Relative rates in plastid-bearing protists. (A) The relative rate of synonymous substitutions in mitochondrial versus plastid genomes (d_S ratio) for various plastid-bearing protists. An mtDNA/ptDNA d_S ratio of ≥1 is shown with a green circle and <1 with a purple circle. (B) Synonymous substitution rates in plastid, mitochondrial, and nuclear genomes. ptDNA is shown in green, mtDNA in blue, and nucDNA in orange. The Archaeplastida comprises glaucophytes (Glauco), red algae, green algae, and land plants, all of which have primary plastids. The haptophyte (Hapto) Phaeocystis and the dinoflagellate (Dino) Symbiodinium have secondary, red–algal-derived plastids. The methods used to estimate d_S and the number and type of loci investigated sometimes differed among the various taxa. The ML approach was used to estimate d_S for all taxa without an asterisk in front of their names. Alternative methods were used for those with an asterisk (see Materials and Methods).