Determination of eye color dominance in the common fruit fly Drosophila melanogaster
Introduction
To determine the inheritance of eye color in Fruit flies (Drosophila melanogaster), two experimental crosses were performed. In one cross, females with white eyes were crossed with males that had red eyes. The other cross females with red eyes were crossed with males who had white eyes. Flies with red eyes carried the wild type trait (w+) flies with white eyes carried the recessive trade (w). In this experiment I will test two hypotheses, one being the red-eye trait is an autosomal-dominant trait, the other the red-eye trait is x-linked dominant.
Methods
After parent generation was crossed for a week (5-8 days), they were removed. This was so they will not be mixed in with the F1 generation. There were two predictions in the crosses of wild-type female x white-eye male. One prediction, if the trait is autosomal dominant, then the F1 progeny will all have the wild-type phenotype which is red-eyes another prediction is if the trait is x-linked dominant, then all the progeny will also have red-eyes.
In the other cross of wild-type male x white-eye female there was also two predictions. One prediction is if the trait is autosomal dominant, then all of the F1 progeny will have the wild-type phenotype which would express red-eyes. The other prediction is if the trait is x-linked dominant, then all of the females of F1 will have red eyes, or the wild-type phenotype, and all the males will have the mutant trait, and would express white-eyes.
Data
Table 1. F1 on the first cross of wild-type females (w+) x white-eye males (w) of fruit flies (D. melanogaster)
Red-Eye (w+) Male
Red-eye (w+) female
White-eye (w) male
White-eye (w) female
Numbers observed
61
39
0
0
Expected H1: Trait is Autosomal Dominant
YES
YES
NO
NO
Expected H2: Trait is X-linked
YES
YES
NO
NO
Table 2. F1 for the second cross of white-eye females (w) x wild-type males (w+) of fruit flies (D. melanogaster)
Red-Eye (w+) Male
Red-eye (w+) female
White-eye (w) male
White-eye (w) female
Numbers observed
0
69
57
0
Expected H1: Trait is Autosomal Dominant
YES
YES
NO
NO
Expected H2: Trait is X-linked
NO
YES
YES
NO
Results
The cross of the wild-type female with a white-eye male can be seen in Table 1. The data found supports both hypotheses. We saw that no white-eye flies appear in our observed values for Table 1. This data supports our predictions for both hypotheses.
The data of the cross of white-eye females and wild-type males are shown in table 2. We can see from table 2, the data ...
