Cytogenetics and karyosystematics of phyllotine rodents (Cricetidae, Sigmodontinae). I. Chromosome multiformity and gonosomal-autosomal translocation in Reithrodon.
The chromosomes of 14 specimens of the genus Reithrodon from three different localities of Argentina and two localities of Uruguay were studied using G- and C-banding techniques. Specimens of Uruguay showed a karyotype of 2n = 28 chromosomes having a large metacentric X, and a telocentric Y chromosome. This karyotype is very similar to that recently described in a sample from southern Brazil, differing only in the nature of the Y chromosome, which is metacentric in the Brazilian form. All specimens from Argentina showed a 2n = 34 karyotype, differing from the Brazilian karyotype by two centric fusions, an acquisition of chromosome material, and at least one pericentric inversion, and by the telocentric nature of both the X and the Y chromosomes. G- and C-banding suggest that the metacentric gonosomes in the Brazilian form resulted from a double autosomal-X-Y Robertsonian translocation. The Uruguayan cytotype is interpreted as derived from a hypothetical neo-X/Y1Y2 ancestral form by the secondary loss of the Y1 chromosome. The karyotypic differences between the Brazilian-Uruguayan and the Argentinian forms afford evidence of species differentiation. It is proposed to assign the former to Reithrodon typicus, and the later to R. auritus.
Ortells
M O
MO
Departamento de Ciencias Biologicas, Universidad de Buenos Aires, Argentina.
Reig
O A
OA
Brum-Zorrilla
N
N
Scaglia
O A
OA
D000818:Animals; D003411:Arvicolinae / Q000235:genetics*; D002871:Chromosome Banding; D005260:Female; D007621:Karyotyping; D008297:Male; D012730:Sex Chromosomes; D014178:Translocation, Genetic