FIG. 6.

Evidence for an SIVcpzPtt lineage ancestral to SIVgor and HIV-1 group O. Trees were inferred for two parts of the Pol1 region in Fig. 4, separated at a putative recombination breakpoint at position 300. Strains are color coded as in Fig. 4. Numbers on internal branches indicate estimated posterior probabilities (only values above 95% are shown). The scale bars represent 0.05 replacements per site. Green, blue, and red circles indicate nodes that were used to calculate the distances shown in Table 1.