Chromosomal phylogeny of Muridae: a study of 10 genera.

The karyotypes of 10 different species of the family Muridae (Acomys airensis, Arvicanthis niloticus, Hylomyscus stella, Malacomys longipes, Mastomys huberti, Myomys daltoni, Mus musculus, Rattus norvegicus, Thamnomys gazellae, and Uranomys ruddi) are compared by different banding techniques. From a reconstruction of the presumed ancestral karyotype of the Muridae the sequence of the various rearrangements leading to the present karyotypes is proposed in order to determine their phylogenetic relationships. In particular, the present karyotypes of the mouse and rat differ from the ancestral one by at least 12 and 7 rearrangements, respectively. A clear tendency for accumulation of a specific type of rearrangement in a given branch of the cladogram is observed. In regard to the mouse, a large number of translocations, with break points situated in the proximal part of the long arms, have occurred, which conserved the acrocentric form of the ancestral chromosomes but led to multiple recombinations of the bands.