Chromosome variability and evolution in rodents of the tribe Abrotrichini (Rodentia, Cricetidae, Sigmodontinae)

DA ROSA, F.A.; OJEDA, A.A.; NOVILLO, A.; LABARONI, C.A.; BUSCHIAZZO, L.M.; TETA, P.; CÁLCENA, E.N.; BOLZÁN, A.D.; OJEDA, R.A.; LANZONE, C.

Mammal Research

springer

Año: 2019 vol. 65 p. 59 - 67

2199-2401

Rodents are a very diverse group with large chromosome variability. One of the most species rich linage in the Neotropics is theSigmodontinae. Among them, the tribe Abrotrichini was recently defined and its taxonomy and phylogeny were mostly elucidatedthrough molecular and morphological evidence. Meanwhile, chromosome data were only secondarily used because offragmentary information. In this contribution, we conduct a chromosome characterization of Abrothrix hirta, A. olivacea,A. andina, and Paynomys macronyx, review the cytogenetic background of the tribe, and contrast it with molecular data.Chromosomes were analyzed by conventional and differential techniques. All Abrothrix species presented 2n = 52/FNa = 56,with a high similarity in the banding patterns reflecting a conserved karyotype, which does not coincide with its high molecularvariability. In turn, P. macronyx have 2n = 54/FNa = 58?59, varying due to a heteromorphic pair of autosomes. In addition, in thislast species, different morphologies of the X chromosome and the presence of B chromosomes were detected. Heterochromatinwas involved in these variants. The telomeric probe in P. macronyx marks terminal regions of all chromosomes. B chromosomesgenerated strong telomeric signals. The Ag-NORs banding revealed the same patterns in Abrothrix and Paynomys. Cytogeneticdata support phylogenetic relationships previously proposed and suggest that the specious genus Abrothrix could have retainedthe ancestral karyotype of the subfamily. In the tribe, the relatively conserved chromosome complement contrasts with its highmolecular variability. This indicates decoupling between the rates of chromosomal and molecular divergence, as observed inother rodent lineages. In abrotrichines, chromosome evolution was slower.