Molecular analysis of populations of Ctenomys (Caviomorpha, Rodentia) with high karyotypic variability.

M. GIMÉNEZ; P. MIROL; C. BIDAU; J. SEARLE

CYTOGENETIC AND GENOME RESEARCH

Año: 2002 p. 130 - 136

1424-8581

Abstract. The tuco-tucos (Ctenomys) are South Americansubterranean rodents that are some of the most chromosomallyvariable of all mammals. In this study we focus on Ctenomys ofthe “Corrientes species group” from that Argentine provinceand consisting of C. dorbignyi, C. perrensi, C. roigi andunnamed populations (Ctenomys sp.). A diploid range of 41–70has been demonstrated for these taxa with multiple Robertsonianchanges, pericentric inversions, heterochromatic modificationsand other chromosomal rearrangements. To analyse themolecular variation in the Corrientes group, a 402 base pairfragment of mitochondrial cytochrome b was sequenced in 75individuals from 26 populations. This generated 15 differenthaplotypes which were subjected to phylogenetic analysis. Thedifferent species within the Corrientes group failed to formmonophyletic groups in the phylogenetic trees we generatedand the divergences between haplotypes were low. Therefore,these molecular data demonstrate the recent subdivision of theCorrientes group with a substantial accumulation of chromosomaldifferences. Through our new chromosomal data andcytochrome b studies, we are able to subdivide the Ctenomyssp. populations into two groups and hypothesize on their relationshipswith the described Corrientes group species. Furtherstudies are needed to establish the basis of the phenomenalchromosomal variation in this group.