Directional-disruptive selection in Drosophila melanogaster.

Artificial directional selection for increased sternopleural chaetae number in Drosophila melanogaster is compared with a mode of directional selection which incorporates an element of disruptive selection. Compared with directional selection, this directional-disruptive selection results in a similar response but with a lower selection differential, and higher realised heritability. The differences might be attributed to a higher genetic variance maintained by the directional-disruptive selection.