Western House Mouse Mus Musculus Research Articles

The Robertsonian phenomenon in the house mouse: mutation, meiosis and speciation.

Many different chromosomal races with reduced chromosome number due to the presence of Robertsonian fusion metacentrics have been described in western Europe and northern Africa, within the distribution area of the western house mouse Mus musculus domesticus. This subspecies of house mouse has become the ideal model for studies to elucidate the processes of chromosome mutation and fixation that lead to the formation of chromosomal races and for studies on the impact of chromosome heterozygosities on reproductive isolation and speciation. In this review, we briefly describe the history of the discovery of the first and subsequent metacentric races in house mice; then, we focus on the molecular composition of the centromeric regions involved in chromosome fusion to examine the molecular characteristics that may explain the great variability of the karyotype that house mice show. The influence that metacentrics exert on the nuclear architecture of the male meiocytes and the consequences on meiotic progression are described to illustrate the impact that chromosomal heterozygosities exert on fertility of house mice-of relevance to reproductive isolation and speciation. The evolutionary significance of the Robertsonian phenomenon in the house mouse is discussed in the final section of this review.

The expansion of the house mouse into north‐western Europe

The western house mouse Mus musculus domesticus is a human commensal, and as such, its phylogeography relates to historical human settlement patterns and movements. We investigate the phylogeography of house mice in northern France and the British Isles (particularly Ireland and the Scottish islands) using microsatellite data and mitochondrial (mt) control region sequences from modern and museum material, placing these in a Europe-wide context. The majority of mtDNA sequences from northern France belong to a clade widespread across the British mainland and Germany, supporting an earlier suggestion that this clade distribution represents colonization by house mice in the Iron Age. The presence of the clade in south-western Ireland indicates possible Iron Age colonization there as well. However, the majority of the Irish sequences belong to a clade elsewhere associated with Norwegian Viking activity, and likely represent the main wave of house mouse colonization of Ireland, arriving from the Scottish islands during the Viking period and linked to urbanization. The St Kilda sequences (from 100-year-old museum samples of the extinct form ‘Mus muralis’ of Barrett-Hamilton) and sequences from South Uist and Lewis also belong to this clade. The clustering of populations shown by the microsatellite data is distinctly different from the mtDNA phylogeny, with populations grouping by geographic proximity, possibly reflecting the genetic effects of secondary colonization. When the mtDNA sequence data are placed in a Europe-wide context, it is clear that the distributions of the two prevalent clades from the vicinity of the British Isles are essentially limited to north-western Europe. These two clades show no evidence of expansion through central Europe, and may therefore reflect maritime colonization.

Mitochondrial DNA variation in the western house mouse (Mus musculus domesticus) close to its site of origin: studies in Turkey

In contrast to a substantial inventory of mitochondrial D-loop sequences from the West European part of the range of the western house mouse Mus musculus domesticus, there are few such data from close to the Middle Eastern origin of the subspecies. This paper attempts to rectify this situation, with details of D-loop sequences of 92 mice from 45 localities in Turkey, adding to the six mice from three localities previously studied from that country. The molecular data were found to be consistent with Turkey being close to the site of origin of M. m. domesticus. The 54 Turkish haplotypes were distributed throughout a phylogenetic tree incorporating representative sequences described previously, and there was high nucleotide diversity among the Turkish mice. There was weak genetic structure in Turkey, although haplotypes of the 'Main Turkish Clade', while common over much of Turkey, were absent from Southern Anatolia. Haplotypes of the Main Turkish Clade were also found in western Europe and it is believed that they derived from Turkey, which thus represents one of the source areas for the westwards expansion of M. m. domesticus.