Some apparently simple relationships involving missing scutellar bristles in scute mutants of Drosophila melanogaster

Abstract

An analysis of the presence or absence of the anterior and posterior scutellar bristles on the left and right sides of scute-bearing Drosophila melanogaster and of the distribution of the 16 possible patterns of the four scutellar bristles among 2893 males suggests the following: (1) that scutellar bristles are commonly present or absent in frequencies involving powers of 1/2; and (2) that observed excesses of symmetrical classes can be accounted for by the detection of potentially asymmetrical flies and their subsequent correction. ‘Corrected’ asymmetrical flies seem to be converted with equal frequencies into one or the other of the corresponding symmetrical ones. An explanatory model has not been constructed; the precise ratios, however, suggest that correspondingly precise chromosomal events are involved.