Molecular events during chromosomal divergence of the South American rodent Graomys griseoflavus

Zambelli A. and Vidal-Rioja L. 1999. Molecular events during chromosomal divergence of the South American rodent Graomys griseoflavus. Acta Theriologica 44: 345-352. Graomys griseoflavus (Waterhouse, 1837) is a South American phyllotine rodent having an autosomal polymorphism produced by a sequence of Robertsonian fusions. The chromosomal divergence was correlated with the molecular organization of two satellite DNA families (EG250 and Hpa3.2) and the second internal transcribed spacer (ITSII) of ribosomal DNA. These studies were performed by Southern hybridization on all G. griseoflavus karyomorphs and other closely related cricetids. When Graomys karyomorphs were compared, interkaryomorphic differences were found at the methyl-ation pat tern level of EG250 satellite and the molecular organization of Hpa3.2 satellite and ITSII. The findings support the hypothesis that Graomys griseoflavus karyomorphs are evolving separately, probably driving a chromosomal speciation process between 2 n = 42-41 and 2n = 38-34 individuals