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 (N_a) 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 (N_p). Ratio N_p/N_a indicates how many paralogs evolved from N_a ancestral genes. Node-specific PHOGs (N_ns) consist of all ancestral PHOGs that did not find their match during the procedure run for all nodes lying higher in the taxonomy tree.

From: PHOG: a database of supergenomes built from proteome complements