PARAPATRIC HYBRIDIZATION IN THE CHROMOSOMAL SPECIATION OF THE HOUSE MOUSE

Chromosomal races of the house mouse (Mus domesticus) occur extensively in Italy. The present paper reports results of studies on a hybrid zone in Central Italy on a chromosomal race with a 2n= 22 karyotype and surrounding populations with a standard 2n= 40 karyotype. Karyotypic and morphometric patterns of variation in this area are discussed in an attempt to contribute to an understanding of the chromosomal speciation in this species. Data are compared, where possible, with other findings on the same hybrid zone. Finally, it is suggested that changes in behavioural traits (inter‐male aggression and female socio‐sexual preferences) may help in promoting complete genetic isolation. Copyright © 1990, Wiley Blackwell. All rights reserved