Location of Shfr, a new gene that rescues hybrid female viability in crosses between Drosophila simulans females and D. melanogaster males.

Abstract

As a rule, progeny of crosses between Drosophila simulans females and D. melanogaster males are formed by sterile males, because females die as embryos. However, populations of these species have been found that produce a certain frequency of viable hybrid females. We have found that 94% of the females of a D. simulans population from Tel Aviv gave hybrid progenies with both sexes. The segregation of phenotypes with different rescue success adjusts to the action of a single, dominant, zygotic-acting gene involved in hybrid female viability. This gene, which we named 'Simulans hybrid females rescue' (Shfr), is temperature-sensitive, showing a much smaller effect as temperature increases. Reciprocal crosses between Tel Aviv and a nonrescue population indicate some influence of cytoplasm or maternal effect in rescue. Using a chromosome substitution analysis we have located Shfr on the second chromosome. Using synthetic lines with this chromosome having different segments from Tel Aviv and from a multimarker strain we have mapped Shfr between black (2 L-43. 0) and pearly (2 R-74.0).