Incomplete dominance occurs when a heterozygote expresses an intermediate phenotype between the two homozygotes. For example, in snapdragons the homozygous dominant RR are red, the homozygous recessive rr are white, and the heterozygous Rr are pink. A monohybrid cross between heterozygous Rr snapdragons will result in a 1:2:1 genotypic ratio and phenotypic ratio of red:pink:white offspring.

1. Monohybrid cross Incomplete dominance

2. Incomplete dominance A kind of dominance occurring in heterozygotes in which the dominant gene or allele is only partially expressed, and usually resulting in an offspring with an intermediate phenotype . Source: http://www.biology-online.org/dictionary/Incomplete_dominance

3. Example: Color in Snapdragons Red snapdragons result from homozygous dominant RR White snapdragons result from homozygous recessive rr Pink snapdragons result from heterozygous Rr

4. Rr X Rr r R r R Alleles

5. Rr X Rr Rr Rr r Rr RR R r R Alleles

6. Genotypic outcomes 3 possible combinations 1 RR homozygous dominant 2 Rr heterozygous 1 rr homozygous recessive Genotypic ratio = 1:2:1

7. Phenotypic outcomes 1 RR red snapdragons 2 Rr pink snapdragons 1 rr white snapdragons Phenotypic ratio = 1:2:1