Fig. 2.
Distribution of the difference in Ka/Ks between the D. sechellia and D. simulans lineages for each pair of orthologous receptor genes (red stripes) and control genes (black stripes). Note that both distributions are shifted to the right of the solid black line at zero (indicating that Ka/Ks tends to be higher in D. sechellia than in D. simulans), but that the distribution for receptors is shifted further to the right than that for controls.