Recombinants between Drosophila Species the F₁ Hybrids of which are Sterile

Abstract

THE genetic analysis of species differences is of especial interest in precisely those cases where the sterility or inviability of the hybrids between the species stands in the way of such analysis. A notable case of this kind is that of Drosophila melanogaster and simulans, species which otherwise would present most favourable conditions for detailed analysis, on account of the already existing knowledge of the genetics of each species and the existence of abundant stocks providing suitable genetic tools (‘markers’). We have found a means of circumventing the sterility of the F₁ hybrids between these species and thus obtaining types of the same kind as would be produced in a backcross of the F₁ hybrid, were it fertile, to melanogaster; it is at the same time possible to recognize, by means of the markers used, what combination of chromosomes is present in the pseudo-backcross progeny and thus to determine the effects of the different chromosome combinations.