Evolution of BRCA1 over the course of primate speciation. A. dN/dS values for each branch of the primate phylogeny were calculated using the free-ratio model in PAML . Branches exhibiting dN/dS values > 1 are shown in bold italics. Dashes (-) represent branches where zero synonymous substitutions are predicted to have occurred. On these branches, dS = 0 and dN/dS can therefore not be calculated. In these instances, the numbers of non-synonymous (N) and synonymous (S) substitutions predicted to have occurred along each branch are indicated in parentheses (N:S). Of these, branches that experienced 4 or more non-synonymous substitutions are in bold italics. Asterisks indicate new sequences generated in this study. B. The human, bonobo, and chimpanzee clade was isolated and dN/dS values were calculated using the one-ratio and two-ratio models in PAML. The two-ratio model was a better fit as determined by the likelihood ratio test shown in the box. ω0 is the calculated dN/dS for all branches under the one-ratio model, or for background branches under the two-ratio model, and ω1 is the dN/dS for the isolated branches in the two-ratio model.