In chickens, comb shape is determined by alleles at two loci (R, r and P, p). A walnut comb is produced when at least one domina
nt allele R is present at one locus and at least one dominant allele P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rr P_). If two recessive alleles are present at the first and at the second locus (rr pp), a single comb is produced. A walnut is crossed with a pea chicken and the offspring consists of 3/8 walnut, 3/8 pea, 1/8 rose and 1/8 single. What are the probable genotypes of the parents
For the recessive trait to be expressed, both parents should have at least 1 allele for the recessive trait. Now you can see that both recessive traits were expressed in at least one of the off-springs, this means that both parents had the allele for each recessive trait.
