Chapter 4, Problem 2EQ

In chickens, some varieties have feathered shanks (legs), but others do not. In a cross between a Black Langhans (feathered shanks) and a Buff Rocks (unfeathered shanks), the shanks of the ${\text{F}}_{\text{1}}$ generation are all feathered. When members of the ${\text{F}}_{\text{1}}$ generation are crossed to each other, the ${\text{F}}_{\text{2}}$ generation has a phenotypic ratio of 15 feathered : 1 unfeathered. Suggest an explanation for this result.