Hybrid dysgenesis in Drosophila melanogaster: no suppressor-X effect on male recombination

Abstract

Large reciprocal differences in the frequency of male recombination and other dysgenic traits are routinely observed in F₁ hybrids between two types of strains designated P and M. In order to determine the genetic basis for this nonreciprocity, experiments were performed to test the alternative hypotheses of suppressor-X chromosome and maternal cytoplasmic effects. The results demonstrated, unambiguously, that there was no major effect of X-chromosome source on male recombination. They also indicated that the maternal cytoplasm, in combination with P autosomes, was clearly related to the frequency of this dysgenic trait. These experiments provide additional support for the contention that hybrid dysgenesis, in both sexes, is dependent on cytoplasm-genome interactions.