Genetics of Chicken Combs

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Multiple Allele Traits in Chickens - The combs of chickens are controlled by four alleles, which interact to produce four distinct phenotypes: single, rose, pea, and walnut. The comb is a fleshy growth on the top of the chicken's head. Both male and female chickens have combs, but the ones on the male are larger. There are four varieties of combs:

chicken combs.png

Punnet squares become unwieldy when multiple alleles are involved. Many of the questions can be solved visually, without using math or a Punnet square. For example the cross rrpp x RRPP will always produce chickens with the genotype RrPp, which will have walnut combs.

chicken cross.png