Relative rates of evolution among the three genetic compartments of the red alga Porphyra differ from those of green plants and do not correlate with genome architecture

► Knowledge of mutation rate is fundamental to understanding genome evolution. ► The nucleotide divergence between species can provide an entrée into mutation rate. ► In plants, mtDNA mutation rates are estimated to be lower than those of ptDNA and nucDNA. ► We show that in the red alga Porphyra the opposite is true. ► The mtDNA mutation rate was 3-5 times greater than those of the ptDNA and nucDNA.