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

Abstract

The cytogenetic study of two populations ofEliomys quercinus L. (R odentia, 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 Eliornys 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.

Comparative cytogenetic and genetic study of two Italian populations of the garden dormouseEliomys quercinusL. (Sciuromorpha: Gliridae)

“…Notwithstanding this problem, differences between the Italian and the Iberian and Iberian-derived populations are evident. The 2n = 48 G-banded karyotypes of the Spanish E. quercinus (Diaz de la Guardia & Ruiz Girela 1979;Arroyo Nombela et al 1982;Sánchez et al 1991) include two "biarmed" chromosomes, which correspond to "uniarmed" chromosomes 9 and 14 in our study. The comparison of the C-and G-banding patterns confirms the presumed pericentric inversions in these chromosome pairs.…”

“…Analysing our cytogenetic data together with available comparable karyotypes from other 2n = 48 populations (Table I), we also noticed certain discrepancies in using chromosome nomenclature (Diaz de la Guardia & Ruiz Girela 1979;Arroyo Nombela et al 1982;Filippucci et al 1988a;Sánchez et al 1991). Notwithstanding this problem, differences between the Italian and the Iberian and Iberian-derived populations are evident.…”

“…One postulates that the most ancient populations of E. quercinus are those of southern Europe (2n = 48), wherefrom they spread northward since Holocene. The higher diploid numbers of the northern populations of the species, in this case, are believed to be due to Robertsonian rearrangements, such as centric fissions of biarmed chromosomes (Arroyo Nombela et al 1982;Filippucci et al 1988a;Filippucci & Capanna 1996). In this context, the presence of a karyotype with 2n = 48 in north-western Russia (Graphodatsky & Fokin 1993) is interesting and could indicate that the process of chromosomal divergence have taken place after the post-glacial dispersal from Mediterranean refugia.…”

Conserved although Very Different Karyotypes in Gliridae and Sciuridae and Their Contribution to Chromosomal Signatures in Glires

“…2 A). The cytotype with 2n = 48 is observed in southern Europe [Arroyo Nombela et al, 1982;da Graca Ramalhinho and Libois, 2001] and, in this study, for the first time in the South of France. The only difference between the 2 cytotypes results from a fission event of a sub-metacentric autosome in 2 acrocentrics, homologous to human chromosome 2q ( fig.…”

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

“…The karyotype is the same as above, but with two more pairs of acrocentric chromosomes in place of one pair of submetacentric (Arroyo-Nombela et al 1982;Filippucci et al 1990;Leonard et al 1970).…”