Mitochondrial DNA and monocot-dicot divergence time

Abstract

Discordant molecular clock estimates of the divergence time between monocots and dicots (angiosperms) have accumulated in recent years. The diverse estimates are more than 100 Myr apart and are derived from nuclear and chloroplast gene sequences. Using two landmark events and nucleotide sequences from 10 mitochondrial genes for which rate homogeneity was formally tested, we have estimated this date to be around 200 Myr. The estimates obtained with the two multiple-gene clocks are highly congruent and in line with previous estimates derived from protein-coding gene sequences from the chloroplast genome. The agreement of this date with recent findings from the fossil record is discussed briefly.