INTEGRATION OF GENOMIC, CHROMOSOMAL AND PHYLOGENETIC LEVELS IN THE RODENT CTENOMYS FROM IBERÁ MARSH, ARGENTINA.

CARABALLO, D. A.; BELLUSCIO, P. M.; ROSSI, S.

Mendoza, Argentina

Congreso; 10th International Mammalogical Congress; 2009

Center for Science & Technology - CCT CONICET Mendoza (CRICYT), National Council of Science and Technology - CONICET, Institute for Aridlands Research - IADIZA, Biodiversity Research Group - GiB, International Federation of Mammalogists - IFM, SAREM

The rodents of the genus Ctenomys (tuco-tucos) conform an extreme case of chromosomal evolution in mammals. The species and forms of tuco-tucos from the Iberá marsh (Corrientes province), are characterized by 3 species with stable karyotypes, and C. sp: a taxonomic undefined complex of populations which exhibit high chromosomal polymorphisms. In previous work, the relationship between nucleotide sequence and the expansion/contraction dynamics of the major satellite DNA of tuco-tucos (RPCS) was studied, for different karyomorphs of the genus. In this work, we studied, in a phylogenetic context, the nucleotide variability distribution and estimated the RPCS copy number, in specimens from the named species that inhabit Corrientes: C. roigi, C. dorbignyi, C. perrensi, and the forms from the C. sp complex. The study was achieved using a PCR strategy to obtain RPCS genomic consensus sequence (gcs) and also to estimate the RPCS copy number per genome by dot blot hybridization. The phylogeny was obtained using a 400 bp fragment pertaining to the D-loop control region.We corroborated the RPCS ancestral library hypothesis, evidenced by the absence of total fixation in unique variants. RPCS copy number varies between 39-2,160 x103 copies per haploid genome. The relationship between RPCS copy number, sequence variability and chromosomal evolution resulted not trivial, but a more robust phylogeny, resulting from the addition of more taxa from the Corrientes Group, is required to conclude the direction of SatDNA and chromosomal evolution.