relative mass of testes

Fertility evaluation of ecologically different forms of house mice and their hybrids of the superspecies complex Mus musculus sensu lato (Rodentia: Muridae)

In house mice from the superspecies complex Mus musculus s.l., the relative weight of their testicles is higher and the sperm quality is better for the exoanthropic species than for the synantropic ones. It is shown that this pattern is observed at an intraspecific level as well, since the testicle weight index and sperm concentration were significantly higher in the hemi-synantropic subspecies Mus musculus wagneri and M. m. gansuensis as compared to the synantropic M. m. musculus in a few comparisons.