Simple Y-autosomal incompatibilities cause hybrid male sterility in reciprocal crosses between Drosophila virilis and D. americana.
Postzygotic reproductive isolation evolves when hybrid incompatibilities accumulate between diverging populations. Here, I examine the genetic basis of hybrid male sterility between two species of Drosophila, Drosophila virilis and D. americana. From these analyses, I reach several conclusions. First, neither species carries any autosomal dominant hybrid male sterility alleles: reciprocal F(1) hybrid males are perfectly fertile. Second, later generation (backcross and F(2)) hybrid male sterility between D. virilis and D. americana is not polygenic. In fact, I identified only three genetically independent incompatibilities that cause hybrid male sterility. Remarkably, each of these incompatibilities involves the Y chromosome. In one direction of the cross, the D. americana Y is incompatible with recessive D. virilis alleles at loci on chromosomes 2 and 5. In the other direction, the D. virilis Y chromosome causes hybrid male sterility in combination with recessive D. americana alleles at a single QTL on chromosome 5. Finally, in contrast with findings from other Drosophila species pairs, the X chromosome has only a modest effect on hybrid male sterility between D. virilis and D. americana.
Sweigart
Andrea L
AL
Department of Biology, University of Rochester, Rochester, New York 14627, USA. asweigar@mail.rochester.edu
D000483:Alleles; D000818:Animals; D002678:Chimera / Q000235:genetics*; D003433:Crosses, Genetic; D004330:Drosophila / Q000235:genetics*; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D040641:Quantitative Trait Loci / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics; D014998:Y Chromosome / Q000235:genetics*