The diverse origins of New Zealand house mice

Molecular markers and morphological characters can help infer the colonization history of organisms. A combination of mitochondrial (mt) d-loop DNA sequences, nuclear DNA data, external measurements and skull characteristics shows that house mice (Mus musculus) in New Zealand and its outlying islands are descended from very diverse sources. The predominant genome is Mus musculus domesticus (from western Europe), but Mus musculus musculus (from central Europe) and Mus musculus castaneus (from southern Asia) are also represented genetically. These subspecies have hybridized to produce combinations of musculus and domesticus nuclear DNA coupled with domesticus mtDNA, and castaneus or musculus mtDNA with domesticus nuclear DNA. The majority of the mice with domesticus mtDNA that we sampled had d-loop sequences identical to two haplotypes common in Britain. This is consistent with long-term British-New Zealand cultural linkages. The origins of the castaneus mtDNA sequences widespread in New Zealand are less easy to identify.