FIG. 24.

Evolutionary relationships within prokaryotes as deduced from signature sequences in various proteins. Although, due to ease of presentation, this figure depicts archaebacteria as distinct from other prokaryotes, the alternate view where archaebacteria are derived from gram-positive bacteria (Fig. 23) is favored based on the available evidence. Beginning with the universal ancestor (〉), the order of evolution of different prokaryotic groups as deduced from signature sequences in different proteins is as shown in this diagram. The asterisks on certain proteins indicate that the timing when these signature sequences were introduced may change with sequence information from additional bacterial phyla. The branching order of various eubacterial groups is consistent with the detailed phylogenies based on Hsp70 and GroEL sequences (Fig. 8 and 11).