Codominance in Chickens: Understanding Feather Color Genetics

Codominance and Genotypes in Chickens

In some chickens, the gene for feather color is controlled by codominance. The allele for black is B and the allele for white is W. The heterozygous phenotype is known as erminette.

Questions:

a. What is the genotype for black chickens?

b. What is the genotype for white chickens?

c. What is the genotype for erminette chickens?

d. If two erminette chickens were crossed, what is the probability that:

i. They would have a black chick?

ii. They would have a white chick?

iii. They would have an erminette chick?

Answer:

Explanation:

Genotype is the genetic composition of organisms and a gene is made up of two alleles.

a) Since the allele for black is B, the genotype for black chickens would be BB.

b) Since the allele for white is W, the genotype for white chickens would be WW.

c) Since erminette color is heterozygous, the genotype would be BW.

d) Two erminette were crossed:

       BW    x    BW

     BB BW BW WW

i. Probability of having black chick (BB) = 25%

ii. Probability of having a white chick (WW) = 25%

iii. Probability of having erminette chicken (BW) = 50%

Final Answer:

In chickens, with codominance for feather color, genotypes would be BB for black, WW for white, and BW for erminette. If two erminette chickens are crossed, there would be a 25% chance for a black or white chick and a 50% chance for an erminette chick.

Explanation:

In genetic studies, the genotype refers to the genetic makeup of an organism. In the case of chickens where the gene for feather color is controlled by codominance, the genotype for each phenotype would be as follows:

• Black chickens would have the genotype BB.
• White chickens would have the genotype WW.
• Erminette chickens (displaying both black and white feathers, because of codominance) would have the genotype BW.