Further evidence for selective differences between isoalleles in Drosophila.

A number of separate strains of Drosophila pseudoobscura were inbred for 38 generations of brother-sister mating with forced heterozygosity for two alleles of either the octanol dehydrogenase or esterase-5 locus. Crosses were set up within each of these inbred lines such that simple mendelian ratios were expected, and eggs from these crosses were placed on media with additions simple chemicals likely to interact with alleles of the two loci--octanol and ethanol for the ODH locus and tributyrin and triacetin for the E-5 locus. Similar crosses were set up involving parental flies with normally heterozygous genetic background as a control.--Significant deviations from mendelian expectation were observed in inbred E-5 flies grown on tributyrin, inbred ODH males grown on octanol, and inbred ODH females grown on ethanol. There was also a strong effect of octanol medium on males of one of the inbred E-5 lines, and a weak effect of tributyrin medium on ODH inbred females.--The probability that these results reflect interactions between these loci and the environment is assessed in the light of differences between the present results and those obtained at earlier stages of inbreeding.