Genetics: Analysis and Principles 5th Edition by Robert Brooker

Exercise 45

In Drosophila, red eyes is the wild-type phenotype. Several different genes (with each gene existing in two or more alleles) are known to affect eye color. One allele causes purple eyes, and a different allele causes sepia eyes. Both of these alleles are recessive compared with red eye color. When flies with purple eyes were crossed to flies with sepia eyes, all of the F 1 offspring had red eyes. When the F 1 offspring were allowed to mate with each other, the following data were obtained:
146 purple eyes
151 sepia eyes
50 purplish sepia eyes
444 red eyes
Explain this pattern of inheritance. Conduct a chi square analysis to see if the experimental data fit your hypothesis.