Comparative karyotype studies between Spanish and French populations of Eliomys quercinus L.

he cytogenetic study of two populations of Eliomys quercinus L. (Rodentia, Gliridae), whose geographic ranges are relatively near, showed that numerical and morphological differences exist between their karyotypes. The French dormouse has a diploid number 2n=50, while the Spanish one had 2n=48. The sex chromosomes and the number of autosomal arms are identical in both populations. The morphological differences are limited to the autosomal metacentric pair 12 of the Spanish dormouse, which does not appear in the French dormouse. However, the latter possesses two pairs of acrocentric chromosomes (20, 24) which are absent in the Spanish dormouse. The bands that correspond to the q and p arms of pair 12 in the Spanish dormouse are identical to pairs 20 and 24 in the French one, respectively. Consequently, we consider the Spanish Eliomys quercinus and the French Eliomys quercinus as having a common ancestor. The Spanish form has originated by means of a Robertsonian translocation, Rb (20, 24), between pairs 20 and 24 of the common ancestor.Peer Reviewe