Drosophila eyes are normally red. Several purple-eyed strains have been isolated as spontaneous mutants, and the purple phenotype has been shown to be inherited as a Mendelian autosomal recessive in each case. To investigate allelism between these different purple mutations, two purple-eyed pure strains were crossed.
If the purple mutations are in the same gene (i.e., they are allelic), the phenotypic ratios in the F1 are expected to be________