Chromosomal variation in Argentine populations of Akodon montensis Thomas, 1913 (Rodentia, Cricetidae, Sigmodontinae).

MALLERET MM; LABARONI CA; GARCÍA GV; FERRO JM; MARTÍ DA; LANZONE C

COMPARATIVE CYTOGENETICS

ZOOLOGICAL INST

Año: 2016 vol. 10 p. 129 - 140

1993-0771

The genus Akodon Meyen, 1983, with about 41 species, is considered one of the most species-rich group within the subfamily Sigmodontinae. Its species are widely distributed in South America and inhabit a variety of habitats, among subtropical and tropical moist forest as well as desert regions (Musser and Carleton 2005). From a taxonomic point of view, the genus includes morphologically very similar species, and cytogenetic data is valuable for identifying them, such as Akodon cursor (Winge, 1887) and A. montensis (Yonenaga-Yassuda et al. 1975; Barros et al. 2009).This genus has high karyotypic variability, with chromosome numbers varying from 2n=46 (FN=46) in A. serrensis Thomas, 1902 to 2n=10 (FN=14) in A. sp. (Barros et al. 2009). Indifferent species, several chromosome variations were described, including pericentric inversions and Robertsonian translocations in autosomes, modifications of sex chromosomes and the presence of B chromosomes (Silva and Yonenaga-Yassuda 1998; Fernández-Donoso et al. 2001; Bianchi 2002).Akodon montensis is an abundant species distributed in Argentina, Brazil and Paraguay, and has a great chromosomal variability (Kasahara and Yonenaga-Yassuda 1982; Musser and Carleton 2005). Previous cytogenetic analysis demonstrated that the standard chromosome complement of A. montensis is 2n=24 (FN=42), with both X and Y chromosomes acrocentric (Yonenaga-Yassuda et al. 1975; Kasahara and YonenagaYassuda 1982; Liascovich and Reig 1989). However, for animals from Brazil, Kasahara and Yonenaga-Yassuda (1982) described a morphological variation for the X chromosome, which was present in both sexes. In populations of Brazil XY fertile females were detected using specific DNA probes from the Y chromosome (Fagundes et al. 2000). Additionally the presence of supernumerary or B chromosomes was reported for specimens from Brazil (Yonenaga-Yassuda et al. 1975; Kasahara and Yonenaga-Yassuda 1982; Di-Nizo et al. 2014). Cytogenetic data on natural populations of A. montensis in Argentina are scarce. Liascovich and Reig (1989) studied four specimens from the Provincial Park ?Islas Malvinas?, in Misiones Province; all specimens had no variations in the standard complement. In order to contribute to the knowledge of karyotypic variability in A. montensis we analyzed specimens from different localities of Misiones Province, Argentina, which is a part of the southernmost area of the range (Pardiñas and Teta 2006).