Physiological Effects of Genes: The Flight of Drosophila Considered in Relation to Gene Mutations

Abstract

The wing-beat frequencies of a wild strain and a number of mutant strains of D. melanogaster were measured stroboscopically during short flights under controlled conditions. The mutant strains used had been made otherwise isogenic with the wild strain either by prolonged back-crossing or by obtaining the mutants anew through x-radiation. The wild strain frequency was 10.36 [plus or minus] 0.06 double beats per minute. A series of mutant types with structural wing modifications did not yield paralFel changes in frequency. E.g., the frequency in the miniature strain was 12.26 [plus or minus]0.11 thousand double beats per min. while the lyra strain, with much larger wing surface, was completely flightless. Some other mutants, such as scute, lobe, cinnabar, etc., showed significant differences from the wild strain. In the white series, some alleles showed significant differences, others did not. The white alleles obtained through x-radiation were similar to the same types made isogenic by backcrossing in having no significant effect on flight. Physiol. studies of mutant types reveal the danger of basing deductions in evolution on purely morph. data.