Quantitative developmental genetic analysis reveals that the ancestral dipteran wing vein prepattern is conserved in Drosophila melanogaster

Quantitative complementation tests provide a quick test of the hypothesis t hat a particular gene contributes to segregating phenotypic variation. A se t of wild-type alleles is assayed for variation in their ability to complem ent the degree of dominance of the quantitative effect of a loss of functio n allele. Analysis of 15 loci known to be involved in wing patterning in Dr osophila melanogaster suggests that the genes decapentaplegic; thickveins, EGFR, argos and hedgehog, each of which are involved in secreted growth fac tor signaling, may contribute to wing shape variation. The phenotype of one deficiency, Df(2R)Px2, which removes blistererd/Plexate, is also highly se nsitive to the wild-type genetic background and at intermediate expressivit y reveals six ectopic veins. These form in the same locations as a projecti on of the ancestral pattern of dipteran wing veins onto the D. melanogaster wing. This atavistic phenotype indicates that the wing vein prepatterning mechanism can be conserved in highly derived species, and implies that homo plasic venation patterns may be produced by derepression of Vein primordia.