Abstract
Segregation Distorter (SD) was found to assort more frequently with the Y-chromosome in SDcn/SD+; XYY males of Drosophila melanogaster. Because gametic and zygotic selection can be eliminated as possible explanations of this non-random assortment, it is suggested that the pairing pattern in the sex chromosomes is changed when segregation distortion occurs. The hypothesis of homology between the SD region and part of the X-chromosome suggested by Hiraizumi and Nakazima (1967) could be one possible explanation.
