FIG. 8.

Ten million years of mouse evolution. The cladogram shows recognized mouse taxa and their relationship as inferred by several molecular techniques. M. m. molossinus, endemic to Japan, is a hybrid of M. m. musculus and M. m. castaneus. The myriad strains of laboratory mouse are derived primarily from the fancy mouse breeding fashionable in Europe (M. m. domesticus) and Japan (M. m. molossinus) in the 19th century. The lighter grey box indicates species derived from a common ancestor before the creation of the West Palearctic species M. spretus, M. macedonicus, and M. spicilegus. Endogenous MLVs have been confirmed to reside only in these species. The darker grey box highlights the HEMV host M. spicilegus (this figure is a composite work from references 2, 5, and 35).