Another Case of Multiple Allelomorphs in Drosophila

Abstract

It has been shown that the factor for white eye color and the factor for eosin eye color are allelomorphs. Each arose as a mutation, but unlike other original and independent mutations they do not give, when crossed, the wild type (red eye) by recombination. Each factor has the same normal allelomorph in the wild fly, and each factor gives the same linkage ratio as the other one with any sex-linked factor. The factor for eosin, the factor for white and their normal allelomorph form a system of triple allelomorphs. Only two of these factors can exist at any one time in the same female, and, since they are sex-linked, only one at a time in a male. In consequence, a red-eyed female may be heterozygous for white or for eosin, but never for white and for eosin.