Evidence for a differentiated chromosomal race north of classical south European refuge areas in the garden dormouse Eliomys quercinus

The dormouse Eliomys quercinus is a forest rodent
undergoing long periods of winter hibernation. The species
presents a surprisingly large diversity of chromosomal races,
which geographic distribution was shown recently to predate
the Pleistocene glaciations. Previously reported data on the
karyotypes of the garden dormouse in France come from the
northeast of the country, where the 2N050 race occurs. New
data are presented from specimens trapped near the Atlantic
coast (departments of Vendée and Charente-Maritime), in the
Pyrenees, the Alps and in the Massif Central. The French
Alpine chain, close to the Italian border, is inhabited by the
2N054 race. A karyotype with 2N048 chromosomes, of
Iberian type, is found north of the Pyrenees, near the central
Atlantic coast and also in the south of the Massif Central, whereas the 2N050 race occurs in the north of the massif. A hybrid between these two races (2N049) was found in Vendée.
These facts reveal that neither the Pyrenees nor the Alps constitute
a biogeographic barrier to the dormouse and strongly
suggest that the present population of northern France derives
from a postglacial recolonisation movement initiated in the
southernmost regions of France or in the Rhône valley.