[The effect of the dominant heat-sensitive mutation l(2)M167(DTS) on the fitness of Drosophila melanogaster heterozygotes at preimaginal stages].

Relative viability of Drosophila melanogaster flies heterozygous for the lethal autosomal temperature-sensitive mutation l(2) M167DTS was studied under permissive conditions. The effect of environmental and genotypic factors on segregation was examined in progeny of reciprocal crosses between the lines l(2)M167DTS SM1 and D-32 (wild type). Comparisons of mass and individual crosses and tests for homogeneity of families and in individual cultures within the total sample imply existence of a complex system of modifiers influenced by culture density and direction of crossing. Correlation analysis of the relationship between larval density and segregation in progeny suggests a threshold level of viability at high density. This causes differences in the composition of progeny of the same parents in mass and individual cultures. These results agree well with the hypothesis on the relationship of population genetic structure and population density.