some thoughts on the association of polled trait and intersexuality in goats一些想法调查协会的特质和雌雄间性山羊.pdf

SOME THOUGHTS ON THE ASSOCIATION OF POLLED TRAIT AND INTERSEXUALITY IN GOATS Parvathi-K. BASRUR Department of Biomedical Sciences Univeysityof Guelph Guelph, Ontario, Canada SUMMARY A cytogenetic mechanism for the association of polledness and intersexuality in dairy goats has been proposed in the light of the existing information on intersexes and sex determination. On the basis of the marked sexual dimorphism for horn in the more primitive members of Bovi- dae and the strong androgen dependence exhibited by the cephalic adornments in general, it is proposed that the determinant of horn in the ancestral species of Goats was located on the Y chromosome in close proximity to, or as part of the maledetermining genes. The presence of horn in females in the more recent species of Bovidae has been attributed to the translocation of a Y chromosome segment to an autosome. According to this hypothesis the development of the horn anlage and the specialization of the somatic blastema cells into Leydig cells of the testes are probably controlled by the same gene (or genes) which were translocated from the Y chromosome to an autosome during the course of evolution in the Caprinae subfamily. The hypotheses advanced by various investigators in the past for the occur- rence of intersexuality in polled goats have been adequately discussed by I,nu- VERGNE in this symposium. In this report an attempt is made to postulate a cytogenetic mechanism for the association of polled trait and intersexuality in dairy goats. Me FEEI.Y, ! al. have suggested that sex determination in Mammals 1967)( including goats may be explained on the basis that the male determining gene on the Y