title: Chromosomal variation in Argentine populations of Akodon montensis Thomas, 1913 (Rodentia, Cricetidae, Sigmodontinae).
abstract: The genus Akodon Meyen, 1833 is one of the most species-rich among sigmodontine rodents and has great chromosome variability. Akodon montensis has a relatively broad distribution in South America, and Argentine populations are located in the southernmost region of its range. Brazilian populations have important chromosomal variability, but cytogenetic data from Argentina are scarce. We performed a chromosome characterization of natural populations of Akodon montensis using conventional staining, C-banding, Ag-NORs and base-specific fluorochromes. A total of 31 specimens from five localities of Misiones Province, in Argentina, were analyzed. The 2n=24 chromosomes was the most frequently observed karyotype. However, five individuals presented 25 chromosomes due to a supernumerary B-chromosome; and one individual had 2n=26 due to one B plus a trisomy for chromosome 11. Additionally, two XY females and two variants of the X chromosomes were found. C-positive centromeric bands occurred in all chromosomes; additional C-bands were observed in some autosomes, the X, Y and B chromosomes. Ag-NORs were observed in five autosomes, and the B chromosome was frequently marked. Fluorochrome banding was similar among karyotypes of the analyzed populations. Comparisons of cytogenetic data among populations of Argentina and Brazil showed the presence of high intraspecific variability in Akodon montensis and some differences among regions.
authors.affiliation: Laboratorio de Genética Evolutiva (LGE) FCEQyN, IBS (CONICET-UNaM), Nodo Posadas, Félix de Azara 1552, CP3300, Posadas, Misiones, Argentina.
authors.forename: Matías Maximiliano
authors.initials: MM
authors.lastname: Malleret
authors.affiliation: Laboratorio de Genética Evolutiva (LGE) FCEQyN, IBS (CONICET-UNaM), Nodo Posadas, Félix de Azara 1552, CP3300, Posadas, Misiones, Argentina.
authors.forename: Carolina Alicia
authors.initials: CA
authors.lastname: Labaroni
authors.affiliation: IBS (CONICET-UNaM), Nodo Iguazú, Bertoni 85, CP3370, Puerto Iguazú, Misiones, Argentina.
authors.forename: Gabriela Verónica
authors.initials: GV
authors.lastname: García
authors.affiliation: Laboratorio de Genética Evolutiva (LGE) FCEQyN, IBS (CONICET-UNaM), Nodo Posadas, Félix de Azara 1552, CP3300, Posadas, Misiones, Argentina.
authors.forename: Juan Martín
authors.initials: JM
authors.lastname: Ferro
authors.affiliation: Laboratorio de Genética Evolutiva (LGE) FCEQyN, IBS (CONICET-UNaM), Nodo Posadas, Félix de Azara 1552, CP3300, Posadas, Misiones, Argentina.
authors.forename: Dardo Andrea
authors.initials: DA
authors.lastname: Martí
authors.affiliation: Laboratorio de Genética Evolutiva (LGE) FCEQyN, IBS (CONICET-UNaM), Nodo Posadas, Félix de Azara 1552, CP3300, Posadas, Misiones, Argentina.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Lanzone
keywords: Ag-NORs; Rodents; chromosome banding; heterochromatin; karyotype variability