Incomplete Dominance - Andalusian Chickens

Alternate Inheritance

1. Incomplete dominance is a form of alternate inheritance in which one allele is not completely dominant over the other.

2. Since one of the alleles is not dominant it creates a third phenotype in the offspring.

3. The third phenotype is a blend of the recessive and dominant phenotypes that the parents possessed.

4. Incomplete dominance only is apparent in the heterozygous offspring.

5. It is also called semidominance.  

Andalusian Chickens

1. The cross-breeding of the black and the white Andalusian chicken produces the blue Andalusian chicken.

2. The ratio of these chickens offspring are 25% black, 50% bluish gray, and 25% white/splash. That is a 1:2:1 ratio.

3. Mendel actually used these chickens in his studies of genetics.

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