As mentioned in Experimental Question E12, red eyes is the wild-type phenotype in Drosophila, and several different genes (with each gene existing in two or more alleles) affect eye color. One allele causes purple eyes, and a different allele causes vermilion eyes. The purple and vermilion alleles are recessive compared with red eye color. The following crosses were made, and the following data were obtained:
Cross 1: Males with vermilion eyes X females with purple eyes
354 offspring, all with red eyes
Cross 2: Males with purple eyes X females with vermilion eyes
212 male offspring with vermilion eyes
221 female offspring with red eyes
Explain the pattern of inheritance based on these results. What additional crosses might you make to confirm your hypothesis?