Hybrid sterility is a common form of reproductive isolation between nascent species. Although hybrid sterility is routinely documented and genetically dissected in speciation studies, its developmental basis is rarely examined, especially in generations beyond the F1. To identify phenotypic and genetic determinants of hybrid male sterility from a developmental perspective, we characterized testis histology in 312 F2 hybrids generated by intercrossing inbred strains of Mus musculus domesticus and M.m. musculus, two subspecies of house mice. Hybrids display a range of histologic abnormalities that indicate defective spermatogenesis. Among these abnormalities, we quantified decreased testis size, reductions in spermatocyte and spermatid number, increased apoptosis of meiosis I spermatocytes, and more multinucleated syncytia. Collectively, our phenotypic data point to defects in meiosis I as a primary barrier to reproduction. We identified seven quantitative trait loci controlling five histologic traits. A region of chromosome 17 that contains Prdm9, a gene known to confer F1 hybrid male sterility, affects multinucleated syncytia, apoptosis of round spermatids, and round spermatid numbers.

Note on studied population: WSB/EiJ x PWD/PhJ intercross

Procedures conducted:

• study archive

Hybrid male sterility. Morphology, sperm count, histopathology.

Ontology terms mapped to Payseur2 measures:

  MA:0000411   testis
  MA:0002765   male germ cell
  MP:0001146   abnormal testis morphology MGI
  MP:0002673   abnormal sperm number MGI
  MP:0004850   abnormal testis weight MGI
  VT:0001146   testis morphology trait
  VT:0001922   male fertility trait
  VT:0002673   sperm quantity
  VT:1000644   testis mass

Investigators	Bret A Payseur       University of Wisconsin,  Madison, WI
Participants	Schwahn DJ, Wang RJ, White MA
Contact	Bret A Payseur     payseur@wisc.edu
Affiliated Center	QTL Archive
Acknowledgements	Funding provided by NIH GM120051 GM007133, NLM2M007359; NSF DEB1353737, DEB0918000; UW-Madison Science and Medicine Graduate Research Scholarship
Project type	QTL Archive data set
MPD identifiers	Payseur2     MPD:640
Data changelog	No updates/corrections.       Initial release date: 01/2019.