Groups of orthology among seventeen Xanthomonas genomes. A cladogram of phylogenetic relationships inferred here is shown on the left. Coloured boxes represent groups of orthologs as detected by OrthoMCL. Each column represents a pattern of presence/absence, and the width of the boxes is proportional to the number of genes showing the given pattern. The colour code is as follows: blue for monophyletic patterns involving all the strains on each species (the pattern including all the genomes coloured light blue); green for evolutionary changes below the species level; and red for patterns involving strains from more than one species and excluding at least one strain of these species. Patterns are ordered by number of genes: columns decrease in number of genes from left to right.