Figure 3
Differences in rates of protein evolution. (A) Prokaryotes versus eukaryotes. Histogram of ratios of eukaryote to prokaryote evolutionary rates. Eukaryotes are derived from three prokaryote lineages: BK-o (31 proteins, blue), BK-m (8 proteins, black), and AK (36 proteins, red). (B) Eukaryotes versus eukaryotes. Protein distances between two species of eukaryotes (KA1 and KA2 in inset) of archaebacterial origin compared with distances between the same two species of eubacterial origin (KB1 and KB2); slope (m) = 2.01. In each case, all sequences being compared are from the same protein. The mirrorlike phylogeny (inset) is the result of horizontal gene transfer and speciation rather than gene duplication.