Data from: Empirical demonstration of hybrid chromosomal races in house mice

Western house mice (Mus musculus domesticus) and common shrews (Sorex
araneus) are important models for study of chromosomal speciation. Both
had ancestral karyotypes consisting of telocentric chromosomes, and each
is subdivided into numerous chromosomal races many of which have resulted
from fixation of new mutations (Robertsonian fusions and whole-arm
reciprocal translocations). However, some chromosomal races in both
species may alternatively have originated through hybridization, with
particular homozygous recombinant products reaching fixation. Here, we
demonstrate the process of generation of hybrid chromosomal races for the
first time in either species using molecular markers. Analysis of
centromeric microsatellite markers show that the Mid Valtellina (IMVA) and
Upper Valtellina (IUVA) chromosomal races of the house mouse are
recombinant products of hybridization of the Lower Valtellina (ILVA) and
Poschiavo (CHPO) chromosomal races, supporting earlier theoretical
analysis. IMVA and IUVA occupy a small area of the Italian Alps where ILVA
makes contact with CHPO. IUVA and CHPO have previously been shown to be
reproductively isolated in one village, emphasizing that hybrid
chromosomal races in small mammals, as in plants, have the potential to be
part of the speciation process.