• Question: Feather colour in hens can be white (WW), black (BB) or speckled (BW). What does this tell you?

    Asked by Esha to Barbara, Matt, Ravinder, Sophie, Tristan on 9 Mar 2015.
    • Photo: Tristan Smith

      Tristan Smith answered on 9 Mar 2015:

      Wow, going back to old school genetics. OK, so the fact that both phenotypes are equally and separately expressed, tells us that these genes show complete codominance. Incomplete codominance would result in grey feathers, both genes are still expressed equally in all cells. In this case however, cells express either black or white, they are both dominant so it becomes random as to which they will express.

    • Photo: Sophie Robinson

      Sophie Robinson answered on 9 Mar 2015:

      This tells you that there are two different forms of the gene that determines feather colour, called alleles. When a hen has two white alleles, one from each parent, it’s feathers are white. When a hen has two black alleles, it’s feathers are black. When a hen has one white and one black allele, its feathers are speckled. Usually, one allele is dominant over another so that having just one copy of the dominant allele means the phenotype will be determined only by that allele. In this case, neither allele is dominant so when they are both present, hens have speckled black and white feathers.

Comments