Mitochondrial DNA sequence variation and evolution of Old World house mice (Mus musculus)

Abstract

We analyzed sequences of two variable segments of the mitochondrial control region (CR) and flanking regions in the house mouse (Mus musculus). Most of the material was sampled from the eastern Mediterranean and the Middle East, i.e., a source area for the colonization of Europe. These sequences were supplemented with other samples from the whole range of the species including the Yemeni island of Socotra. This island was shown to harbour mice bearing M. m. domesticus and M. m. castaneus CR haplotypes. In addition, we found 10 distinct sequences at the same locality that were markedly different from all known CR sequences. Sequencing of the whole mitochondrial genome suggested these sequences to represent nuclear fragments of the mitochondrial origin (numts). We assessed genetic variation and phylogeography within and among the house mouse subspecies and estimated the substitution rate, coalescence times, and times of population expansion. We show the data to be consistent with time dependency of substitution rates and recent expansion of mouse populations. The expansion of European populations of M. m. musculus and M. m. domesticus estimated from the CR sequences coincide with presumed time of colonization of the continent in the Holocene.