Chapter 2, Problem 45P

Domestic dogs evolved from ancestral grey wolves. Wolves have coats of short, straight hair and lack “fur-nishings,” a growth pattern marked by eyebrows and a mustache found in some domestic dogs. In domestic dogs, coat variation is controlled by allelic variation in three genes. Recessive mutant alleles in the FGF5 gene result in long hair, while dogs carrying the dominant ancestral allele have short hair. Likewise, recessive mutant alleles in the KRT71 gene result in curly hair, whereas dogs with an ancestral dominant allele have straight hair. Dominant mutant alleles in the RSPO2 gene cause the presence of furnishings, while dogs homozygous for the ancestral recessive allele have no furnishings.

A pure-breeding curly-and long-haired poodle with furnishings was crossed to a pure-breeding short-and straight-haired border collie lacking furnishings.

a. What are the genotypes and phenotypes of the puppies?

b. If dogs of the $F_1$ generation are interbred, what propor-tions of genotypes and phenotypes are expected in the $F_2$?