Incomplete Dominance or Codominance

Incomplete Dominance

– there is an interaction between 2 alleles in the homozygous form

– alleles are semi – or incompletely dominant and act together to yield an intermediate heterozygote – usually phenotypically between the two homozygote

Codominance

– when definite product or substance controlled by each allele is identified

ex. of incomplete dominance:

Andalusian Fowl – has gene that determines feather colour

2 blue feathers (Bb) – give following offspring:

1 black (BB)

2 blue (Bb)

1 white with black splashes (bb)

Black (BB)   X   white (bb)   = all blue (Bb)