Integrative analysis of chromosome banding, telomere localization and molecular genetics in the highly variable Ctenomys of the Corrientes group (Rodentia; Ctenomyidae)

BUSCHIAZZO, L. M.; CARABALLO, D. A.; CÁLCENA, E.; LONGARZO, M. L.; LABARONI, C. A.; FERRO, J. M.; ROSSI, M. S.; BOLZÁN, A. D.; LANZONE, CECILIA

GENETICA

SPRINGER

Lugar: Berlin; Año: 2018

0016-6707

The genus Ctenomys comprises about 70 species with great chromosome diversity. The Corrientes group is one of the mostchromosomally variable lineages in the genus, where the diploid number (2n) varies from 41 to 70. In this group, threenominal species and numerous polymorphic and polytypic populations have been described. In order to get insight into thechromosomal evolution of this species complex, we applied different banding and molecular cytogenetic techniques. Theresults were interpreted in an evolutionary context, based on mitochondrial cytochrome b analyses. Studied samples arerepresentative of the broad chromosomal variability in the group, including specimens with 2n = 42 to 2n = 70. Heterochromatinwas scarce but concentrated in a few chromosomes. Centromeric DAPI-negative heterochromatin was observed insome autosomal pairs, which differed among populations. Location and amount of DAPI-neutral heterochromatin withinthe Y chromosome varied among populations. The variable distribution of heterochromatin indicates its dynamic behavior.NORs were detected in one pair of autosomes, which also differed among some populations. Telomeric FISH signals wereobserved in all complements only at the chromosome ends. The Corrientes group belongs to a clade that also includes C.pearsoni, C. lami, C. minutus, C. ibicuiensis and C. torquatus. Almost all of these species are variable at the chromosomallevel, suggesting that this is the ancestral condition of the clade. Within the Corrientes group, the observed low geneticdivergence, in contrast with its high chromosomal variability, is indicative of decoupling between the rates of chromosomaland mitochondrial evolution.