Question

Although most behaviors are complex traits influenced by several genes, some behavioral differences among individuals can be ascribed to alleles of a single gene (for example, the period gene in Drosophila). Mice that are mutant for the waltzer gene run around in circles, shake their heads both horizontally and vertically, and are very irritable. Four matings among animals isolated from a small population containing waltzer yielded the following litters:

Wildtype X waltzer 3 wildtype, 2 waltzer
Wildtype Xwildtype 7 wildtype
Wildtype Xwildtype 6 wildtype, 2 waltzer
Waltzer Xwaltzer 5 waltzer
Judged on the basis of these data, do you think it is likely that the waltzer allele is dominant or recessive to the wildtype allele?

Answer 1

Based on the results of the matings, the waltzer allele is likely recessive to the wildtype allele.

Step-by-step explanation:

To determine whether the waltzer allele is dominant or recessive to the wildtype allele, we can analyze the results of the matings. In the first cross between a wildtype and waltzer mouse, 3 wildtype and 2 waltzer offspring were produced. This suggests that the waltzer allele is recessive to the wildtype allele. In the other matings, where both parents were wildtype or both were waltzer, only wildtype or waltzer offspring were produced, indicating that the wildtype allele is dominant.