Multiple autosomal polymorphism in populations of Akodon simulator simulator Thomas, 1916 from Tucum�n, Argentina (Rodentia, Cricetidae)

Abstract

Cytogenetic analysis was performed on twenty seven specimens of Akodon simulator simulator collected in three different localities of Tucumfin Province, Argentina. Diploid number, chromosomal morphology and C and G banding patterns were studied. Eight different karyomorphs were found, with diploid numbers of 2n = 38, 39, 40, 41, and 42. All individuals showed the same number of chromosomal arms (FN = 42). G-bands enable to identify chromosomal pairs (1, 10, 11, 12, 13, and 14) involved in three centric fusions. C-bands revealed that the heterochromatin is located in centromeric regions of the telocentric and biarmed chromosomes. The present study allowed us to document a new example of a floating multiple Robertsonian fusion polymorphism. The data are discussed in relation to the occurrence of Robertsonian polymorphism in natural populations. ResumenPolimorfismo autos6mico mtiltiple en poblaciones de Akodon simulator simulator Thomas, 1916 de Tucum~in, Argentina (Rodentia, Cricetidae). Se realiz6 un andlisis citogen6tico de 27 especimenes de Akodon simulator simulator colectados en tres localidades diferentes de la provincia de Tucumfin, Argentina. Se determin6 el nfimero diploide, la morfologia cromos6mica y los patrones de bandeo C y G. Se encotraron 8 cariomorfos diferentes, con nfimeros diploides de 2n ---38, 39, 40, 41, y 42. Todos los individuos presentaron el mismo ntimero de brazos cromos6micos (FN = 42). Las bandas G permitieron identificar los pares cromos6micos (1, 10, I 1, 12, 13, y 14) involucrados en tres fusiones c6ntricas y las bandas C revelaron que la heterocromatina estfi localizada en las regiones centrom6ricas de los cromosomas teloc6ntricos y de los cromosomas bibraquiados. E1 presente estudio nos permite analizar un nuevo ejemplo de un polimorfismo robertsoniano. Los datos son discutidos en relaci6n con la presencia de los polimorfismos robertsonianos en la naturaleza.

Chromosomal and Synaptonemal Complex Analysis of Robertsonian Polymorphisms in Akodon dolores and Akodon molinae (Rodentia, Cricetidae) and their Hybrids.

“…Otherwise, such high levels of heterozygosity would be unbearable. A similar situation seems to be present in the populations of the related species, Akodon simulator, polymorphic for three Robertsonian translocations (Liascovich et al 1990). …”

Karyological geographic variation of Oligoryzomys nigripes Olfers, 1818 (Rodentia, Cricetidae) from Brazil

“…The major difficulty is determining patterns of rearrangements occurrence because of either small sampling or insufficient number of geographical areas studied (Bianchi et al, 1969;Liascovich et al, 1990;Sbalqueiro et al, 1991;Castro et al, 1991;Andrades-Miranda et al, 2001;Wang et al, 2003b).…”