Men and mice: mouse population genetics in the Aeolian Archipelago

The problem concerning karyotype variability in mice (Mus musculus domesticus), and its role in speciation arose last century when, in the Poschiavo Valley (Grisons Canton, Switzerland), Alfred Gropp found an isolated population of Mus musculus (at that time considered a different species, i.e., Mus poschiavinus Fatio 1869, the tobacco mouse). This population was characterised by a karyotype of 26 chromosomes, formed by means of seven centric fusions from the 40 chromosomes, all acrocentrics, of the standard karyotype (Gropp et al. 1970). It is now forty years later, and while a number of distinguished evolutionists from every part of the world have studied this problem, several aspects of this fascinating model of speciation in progress have not been completely solved.