Non-mendelian female sterility and hybrid dysgenesis inDrosophila melanogaster

Abstract

SUMMARY: Systematic crosses between various strains ofDrosophila melanogasterlead in some cases to partly sterile F₁females (SFfemales). Two main classes of strain, inducer and reactive, have been denned on the basis of this sterility, which shows very specific physiological features.SFfemales arise only when reactive females are crossed with inducer males. In contrast, F₁females (RSF) produced by the reciprocal cross between inducer females and reactive males have normal fertility. All wild populations tested are of the inducer category, laboratory strains are either inducer or reactive. Sterility is the result of interaction between two genetic factors denotedIandR, respectively responsible for the inducer and reactive conditions and whose unusual genetic behaviour has been described in other papers. The present paper reports experiments showing that theI–Rinteraction is also responsible for high levels ofXnondisjunction and of mutation in theSFfemale germ-line. The analogy with the P-M system of Kidwell, Kidwell & Sved (1977b), is discussed as are also the implications of the existence of theI-Rsystem for spontaneous mutation research inD. melanogaster.