Figure 1. Simplified phylogeny depicting the relationships among muroid rodent model organisms.
Peromyscus belong to the Cricetidae family, which includes voles (Microtus), hamsters (Mesocricetus), and New World rats and mice. Old World rats and mice belong to the Muridae family, which include the familiar laboratory rat (Rattus norvegicus) and mouse (Mus musculus). Muridae and Cricetidae diverged roughly 25 million years ago. Schematic based on based on phylogeny data from Steppan et al. (2004). Image credit, Nicole Bedford and Hopi Hoekstra.