Cytogenetic differentiation of species from the genus Rattus (Rodentia, Muridae) from the Dalat Plateau in Southern Vietnam

摘要

Chromosome sets in four species of the genus Rattus (R. cf. rattus, R, cf. losea, R. exulans. R. koratensis) collected in the Dalat Plateau (Southern Viemam) were studied. Morphology of R. cf. rattus, R. cf. losea, R. exulans chromosomes (2n = 42, NF = 60) is similar at the level of routinae staining, but R. koratensis differs from the other investigated forms (2n = 42, NF = 70) in karyotype structure. Interspecies variability in heterochromatin quality and localization has been revealed in the compared species. Large intensively coloured pericentromeric blocks of heterochromatin prevail in R. cf. rattus and R. cf. losea. C-banding reveals a small quantity of heterochromatin in the karyotype of R. exulans that is concentrated in the fully heterochromatinized Y-chromosome, in intercalaric blocks of chromosome I and in pericentromeric regions of several pairs of autosomes. Contribution of chromosome rearrangements, related to variability of heterochromatin in short arms of subtelocentric autosomes, into karyotypic evolution of the genus Rattus has been confirmed for the first time from R. koratensis, characteristic of a wide spectrum of heterochromatin localization. Taxonomic and phylogenetic aspects of the results obtained are discussed.