Many alleles for the white eye phenotype have been identified in Drosophila. Some of them are listed on the right. The incomplete dominance manifest in these alleles can be seen by examining the pigment content of heterozygotes arising from selected matings among certain homozygote strains. The lower table lists a few heterozygotes. See if you can determine the parental cross from the upper table that produced the heterozygote in the lower table. Enter your selection below and then click on the heterozygote value in the lower table to get the answer.
0.1114 =
0.8700 =
0.9220 =
1.0546 =
Note that in many cases, the heterozygote pigment is intermediate between the pigment values of the parent... suggesting that the genes are incompletely dominant. Note also that this table provides a simple mechanism to explain one aspect of multiple alleles. Mutant enzymes in the pigment forming system will produce minute differences in the amount of pigment displayed by the eye. These differences are genetically transmitted and constitute specific phenotypes. The different mutations affect to different degrees the amount of pigment in the eye.
