Figure 2. The frequency of amino acid substitutions attributable to positive selection in the D. melanogaster lineage (left bars) and the D. simulans lineage (right bars).
A+: beneficial substitutions (γ>0) attributable to selection. D+: beneficial substitutions (γ>0) attributable to drift. D0: neutral substitutions (γ = 0) attributable to drift. D–: deleterious substitutions (γ<0) attributable to drift.
