MITOCHONDRIAL-DNA AND MONOCOT-DICOT DIVERGENCE TIME

Discordant molecular clock estimates of the divergence time between mo nocots and dicots (angiosperms) have accumulated in recent years. The diverse estimates are more than 100 Myr apart and are derived from nuc lear and chloroplast gene sequences. Using two landmark events and nuc leotide sequences from 10 mitochondrial genes for which rate homogenei ty was formally tested, we have estimated this date to be around 200 M yr. The estimates obtained with the two multiple-gene clocks are highl y congruent and in line with previous estimates derived from protein-c oding gene sequences from the chloroplast genome. The agreement of thi s date with recent findings from the fossil record is discussed briefl y.