The estimated rate of adaptive substitution in different classes of gene.

Estimates from a single Kenyan population sample from each of D. melanogaster and D. simulans, and the divergence between them. (A) estimates of the proportion of non-synonymous substitutions that were adaptive (α). (B) estimates of the number of adaptive non-synonymous substitutions per non-synonymous site (a). P-values are with respect to the control genes, and were determined by bootstrapping. Error bars are 95% bootstrap intervals around the mean, calculated across loci.