A further study of interchromosomal epistatic interaction in male mating activity of Drosophila melanogaster.

The interchromosomal epistatic interaction between second and third chromosomes was investigated for male mating activity of Drosophila melanogaster. The observed mating activity of double chromosome homozygotes is 0.526 +/- 0.044, whereas the expected one under the multiplicative model is calculated to be 0.511 +/- 0.038. These two male mating activities are in excellent agreement, indicating no interchromosomal epistasis. The coefficient of interaction, i, is quantified as -0.174 +/- 0.168. The magnitude of the k statistic, another index of epistasis, is 0.0001 +/- 0.0267. Neither index of epistasis differs statistically from zero. The result also shows that there is little or no epistatic interaction between two major chromosomes. However, one interchromosomal synthetic sterility was found in 26 chromosome lines. These results are combined with those of Kosuda (1985) and the generality of epistatic interaction is discussed.