Similar rates of protein adaptation in <Emphasis Type="Italic">Drosophila miranda</Emphasis> and <Emphasis Type="Italic">D. melanogaster</Emphasis>, two species with different current effective population sizes

Background  

Adaptive protein evolution is common in several Drosophila species investigated. Some studies point to very weak selection operating on amino-acid mutations, with average selection intensities on the order of N _e s ~ 5 in D. melanogaster and D. simulans. Species with lower effective population sizes should undergo less adaptation since they generate fewer mutations and selection is ineffective on a greater proportion of beneficial mutations.