Functional distribution of genes in the cyanobacterial genomes. The distribution of functions for the most recent common ancestor (MRCA) of cyanobacteria is shown at the top. Clade 1 and Clade 2 cyanobacteria are shaded in green and blue in the phylogeny, respectively. At the bottom of the plot is the distribution for chloroplasts (averaged over 189 genomes with a total of 17,216 genes). Note that the chloroplast plot has its own colour key (bottom). COG categories are ordered according to maximum contribution in a single genome. Some Clade 1 cyanobacteria appear to have a higher distribution of genes related to Replication (L), Signal transduction mechanisms (T) and Cell motility (N), while functions related to Amino acid metabolism (E) and Posttranslational modification and chaperones (O) are more abundant in Clade 2. Pseudogenes have been excluded from this analysis. COG abbreviations are as in Figure 2.