Figure 1

Hierarchical cluster analysis with bootstrap resampling method was performed on the complete set of organisms (columns of the phylogenetic profile matrix). The number of genes identified in each organism (with a similarity measure greater than zero) is reported as a gray histogram below the dendrogram. Organism taxonomies are highlighted with different colors: γ proteobacteria in blue, β proteobacteria in red, α proteobacteria in green, δ proteobacteria in light blue and others in black.