Genetics of factors affecting the life history of Drosophila melanogaster. IV. Cytoplasmic/maternal factors affect egg insertion behavior.

The genetic basis of insertion behavior of laboratory strains of Drosophila melanogaster was examined. Reciprocal crosses among five strains revealed a significant effect of interaction between cytoplasmic/maternal factors and the chromosomal genotype in determining the insertion tendency, thus complicating the characterization of the dominant/recessive nature of the insertion genes. The majority of heterozygous combinations demonstrated dominance or partial dominance for the higher insertion tendency over low insertion, while a few combinations produced results to the contrary. These could be due to a more complex genetic basis of insertion behavior than a simple dominant/recessive relationship or else to the cytoplasmic/maternal-chromosome interactions. Examination of the effects of each chromosome revealed the greatest contributions to insertion tendency from the second and third chromosomes, with a significant effect of interaction or nonadditivity of the insertion genes in these two chromosomes in the genotypes tested. The X and fourth chromosomes appear to contribute a small effect in some strains.