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Genetics of Chicken Combs

  • Page ID
    21246
  • 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

    For each cross, indicate the expected phenotypes.

    1. Rose comb (RrPp) and Pea Comb (rrPP)

    Single _____
    Rose ____
    Pea ____
    Walnut ____

    2. Single comb x Walnut (RrPp)

    Single _____
    Rose ____
    Pea ____
    Walnut ____


    3. Single comb x Pea comb (rrPp)

    Single _____
    Rose ____
    Pea ____
    Walnut ____

    4. Single comb x Pea comb (rrPP)

    Single _____
    Rose ____
    Pea ____
    Walnut ____

    5. Walnut combs (both heterozygotes) RrPp x RrPp

    Single _____
    Rose ____
    Pea ____
    Walnut ____