title: X-y interactions underlie sperm head abnormality in hybrid male house mice.
abstract: The genetic basis of hybrid male sterility in house mice is complex, highly polygenic, and strongly X linked. Previous work suggested that there might be interactions between the Mus musculus musculus X and the M. m. domesticus Y with a large negative effect on sperm head morphology in hybrid males with an F1 autosomal background. To test this, we introgressed the M. m. domesticus Y onto a M. m. musculus background and measured the change in sperm morphology, testis weight, and sperm count across early backcross generations and in 11th generation backcross males in which the opportunity for X-autosome incompatibilities is effectively eliminated. We found that abnormality in sperm morphology persists in M. m. domesticus Y introgression males, and that this phenotype is rescued by M. m. domesticus introgressions on the X chromosome. In contrast, the severe reductions in testis weight and sperm count that characterize F1 males were eliminated after one generation of backcrossing. These results indicate that X-Y incompatibilities contribute specifically to sperm morphology. In contrast, X-autosome incompatibilities contribute to low testis weight, low sperm count, and sperm morphology. Restoration of normal testis weight and sperm count in first generation backcross males suggests that a small number of complex incompatibilities between loci on the M. m. musculus X and the M. m. domesticus autosomes underlie F1 male sterility. Together, these results provide insight into the genetic architecture of F1 male sterility and help to explain genome-wide patterns of introgression across the house mouse hybrid zone.
authors: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721.
authors: Polly
authors: P
authors: Campbell
authors: Michael W
authors: MW
authors: Nachman
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D005260:Female; D006824:Hybridization, Genetic; D007248:Infertility, Male / Q000235:genetics*; D008297:Male; D051379:Mice / Q000145:classification / Q000235:genetics* / Q000502:physiology; D008815:Mice, Inbred Strains; D009929:Organ Size; D010641:Phenotype; D012098:Reproduction; D012730:Sex Chromosomes / Q000378:metabolism*; D013076:Sperm Count; D013077:Sperm Head / Q000473:pathology*; D013737:Testis / Q000002:abnormalities / Q000473:pathology
keywords: Dobzhansky–Muller incompatibilities; negative epistasis; sex chromosomes; speciation; spermiogenesis