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Abstract

Background: The phylogeography of the house mouse (Mus musculus L.), an emblematic species for genetic and
biomedical studies, is only partly understood, essentially because of a sampling bias towards its most peripheral
populations in Europe, Asia and the Americas. Moreover, the present-day phylogeographic hypotheses stem mostly
from the study of mitochondrial lineages. In this article, we complement the mtDNA studies with a comprehensive
survey of nuclear markers (19 microsatellite loci) typed in 963 individuals from 47 population samples, with an
emphasis on the putative Middle-Eastern centre of dispersal of the species.
Results: Based on correspondence analysis, distance and allele-sharing trees, we find a good coherence between
geographical origin and genetic make-up of the populations. We thus confirm the clear distinction of the three best
described peripheral subspecies, M. m. musculus, M. m. domesticus and M. m. castaneus. A large diversity was found
in the Iranian populations, which have had an unclear taxonomic status to date. In addition to samples with clear
affiliation to M. m. musculus and M. m. domesticus, we find two genetic groups in Central and South East Iran, which
are as distinct from each other as they are from the south-east Asian M. m. castaneus. These groups were previously
also found to harbor distinct mitochondrial haplotypes.
Conclusion: We propose that the Iranian plateau is home to two more taxonomic units displaying complex
primary and secondary relationships with their long recognized neighbours. This central region emerges as the area
with the highest known diversity of mouse lineages within a restricted geographical area, designating it as the focal
place to study the mechanisms of speciation and diversification of this species.