Positioning of 47 complete-genome organisms on a 16S rRNA tree (phylogram view). Among these, seven 16S rRNA subtree regions are color-coded to facilitate comparison with the TCG regions on the Trp-protein concatenate tree of Fig. 2. Dashed lines in orange indicate organisms representing lineages where genomes of close relatives have not yet been sequenced. A grey box indicates a region of minimal current genome representation that is expected to become a region of subtree congruency. The subdivisions of the Proteobacteria are labelled at the lower right. Note that it is an idiosyncracy of tree presentation that Tfe and Xfa appear to group more closely with beta-proteobacteria than with other gamma-proteobacteria. However, it is a distance tree and close inspection of the distances reveal the identity of the gamma-proteobacteria as a single, cohesive group. The horizontal bar corresponds to 0.1 substitutions per site on the distance tree.