CHROMOSOMAL EVOLUTION IN BOVIDS - A COMPARISON OF CATTLE, SHEEP AND GOAT G-BANDED AND R-BANDED CHROMOSOMES AND CYTOGENETIC DIVERGENCES AMONG CATTLE, GOAT AND RIVER BUFFALO SEX-CHROMOSOMES

A G- and R-banding comparison of cattle (sos taurus, 2n = 60), goat (Capra hircus, 2n = 60) and sheep (Ovis aries, 2n = 54) chromosomes at the 450 band level was made. The study revealed a large number of banding homologies among the autosomes of the three species and resolved some ambiguities in arranging some of their small disputed acrocentrics by direct and indirect comparisons with some bovid marker chromosomes. A loss of the subcentromeric G-positive band in sheep chromosome 2q was observed when the G-banding patterns of sheep 2q and homologous cattle and goat chromosome 2 were compared. The chromosomal divergences among cattle, goat and river buffalo (Bubalus bubalis, 2n = 50) sex chromosomes are shown to have occurred by pericentric and paracentric inversions with a loss (or acquisition) of constitutive heterochromatin.