Chapter 12, Problem 14TYK

In chickens, feathered legs are produced by a dominant allele F. Another allele f of the same gene produces featherless legs. The dominant allele P of a gene at a different locus produces pea combs; a recessive allele p of this gene causes single combs. A breeder makes the following crosses with birds 1, 2, 3, and 4; all parents have both feathered legs and pea combs:

Cross Offspring

$1\times 2$ All feathered, pea comb

$1\times 3$ 3/4 feathered; 1/4 featherless, all pea comb

$1\times 4$ 9/16 feathered, pea comb; 3/16 featherless, pea comb 3/16 feathered, single comb; 1/16 featherless, single comb

What are the genotypes of the four birds?