Table 1.
Number of PHOGs obtained at the nodes of the taxonomy tree for the lineage leading from the Universal Common Ancestor to Escherichia coli O157. For each node, ancestral PHOGs (Na) contain two or more PHOGs from its child nodes that were declared as orthologs and possibly some PHOGs from child nodes that were declared as paralogs (Np). Ratio Np/Na indicates how many paralogs evolved from Na ancestral genes. Node-specific PHOGs (Nns) consist of all ancestral PHOGs that did not find their match during the procedure run for all nodes lying higher in the taxonomy tree.
| Node of the taxonomy tree | Escherichia coli O157 | Escherichia | Enterobacteriales | Gamma-proteobacteria | Proteobacteria | Bacteria | Universal common ancestor |
| Total number of PHOGs, N | 5196 | 5276 | 11868 | 17058 | 23915 | 38234 | 51367 |
| Number of node-specific PHOGs, Nns | 578 | 161 | 1327 | 934 | 996 | 2079 | 2055 |
| Number of ancestral PHOGs, Na | 5196 | 3780 | 5190 | 3766 | 3104 | 3827 | 2055 |
| Number of paralogs, Np | 0 | 629 | 3101 | 2373 | 1576 | 2453 | 1620 |
| Np/Na | 0 | 0.166 | 0.597 | 0.63 | 0.507 | 0.64 | 0.788 |