Studies of the species barrier between drosophila subobscura and d. Madeirensis i. the genetics of male hybrid sterility

Abstract

The genetics of hybrid male sterility between Drosophila subobscura and D. madeirensis were studied with the help of 20 markers in backcross males. A major effect resides in the sex chromosomes: backcross males with the X and Y of different origin (mad X-sub Y or sub X-mad Y) have very small and empty testes. In compatible combinations testes are of normal size but males may be sterile or fertile depending on the genetic constitution of their autosomes. Six autosomal factors affecting hybrid male fertility could be postulated. This estimation is based on the assumption of the absence of interaction between viability and fertility. The presence and the mode of such interaction may modify the number of sterility factors. © 1991 The Genetical Society of Great Britain.