Figure 3.
Evolutionary tree of the genus Mus (the time scale is in millions of years, Myrs). The branch leading to the subgenus Mus encompasses all of the species with a basic karyotype of 2N = 40 acrocentric chromosomes. Today's classical laboratory strains are recombinant strains derived (in unequal percentages) from three parental components: Mus musculus domesticus, Mus musculus musculus, and Mus musculus castaneus. Hybrids between mice of the Mus musculus complex are viable and most are also fertile in both sexes. Hybrids of the Mus musculus complex with Mus spretus or Mus spicilegus are viable but male sterile. (Redrawn with permission from Elsevier © 2003, Guénet and Bonhomme 2003.)
