Genetics: Analysis and Principles 5th Edition by Robert Brooker

Exercise 44

A particular breed of dog can have long hair or short hair. When true-breeding long-haired animals were crossed to true-breeding short-haired animals, the offspring all had long hair. The F 2 generation produced a 3:1 ratio of long- to short-haired offspring. A second gene affects the texture of the hair. The two variants are wiry hair and straight hair. F 1 offspring from a cross of these two varieties all had wiry hair, and F 2 offspring showed a 3:1 ratio of wiry-haired to straight-haired puppies. Recently, a breeder of the short-, wiry-haired dogs found a female puppy that was albino. Similarly, another breeder of the long-, straight-haired dogs found a male puppy that was albino. Because the albino trait is always due to a recessive allele, the two breeders got together and mated the two dogs. Surprisingly, all of the puppies in the litter had black hair. How would you explain this result