Table 4.

List of organisms used in the study; set4org contains genomes used in ortholog groups that span four organisms in each subgroup (A, G, or P) and set6org contains genomes used in ortholog groups that spans six organisms for each subgroup.

Group	Organism
Archaea	▶ Archaeoglobus fulgidus
	▶ Halobacterium sp. NRC-1
	▶ Methanococcus jannaschii
	▶ Pyrobaculum aerophilum
	Pyrococcus abyssi
	Thermoplasma acidophilum
Proteobacteria	▶ Caulobacter vibrioides
	▶ Escherichia coli O157:H7
	▶ Pseudomonas aeruginosa
	▶ Sinorhizobium meliloti
	Haemophilus influenzae
	Rickettsia prowazekii
Grampositive bacteria	▶ Bacillus subtilis
	▶ Escherichia coli O157:H7
	▶ Pseudomonas aeruginosa
	▶ Sinorhizobium meliloti
	Haemophilus influenzae
	Rickettsia prowazekii

▶ genomes included in set4org