Fragmentation of ancestral chloroplast gene clusters during the evolution of the Zygnematales. The ancestral clusters shown are found in both Mesostigma [GenBank:NC_002186] and Marchantia [GenBank:NC_001319] cpDNAs. The top and bottom arrows denote the sites where they are broken in Staurastrum and Zygnema cpDNAs, respectively. For the polarities of the genes relative to one another, the reader should consult the gene map of Mesostigma cpDNA .
Turmel et al. BMC Biology 2005 3:22 doi:10.1186/1741-7007-3-22