Table 1 The topology that places M. m. castaneus sister to M. m. musculus was sampled most frequently, whether a ghost population was included or not. The three subspecies are numbered from 0 to 2 (corresponding to M. m. castaneus, M. m. domesticus, and M. m. musculus, respectively). Ancestral populations are numbered beginning with 3 and are ordered numerically in time (i.e. 4 is the ancestor of all populations). When a ghost population is included, it is an outgroup to the sampled subspecies and has not been included in the species tree notation