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Definition

noun

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.

Supplement

In incomplete dominance, a heterozygous organism carrying two alleles wherein one is dominant and the other one is recessive, (e.g. Aa), the dominant allele will only be partially expressed. Hence, the heterozygote (Aa) will have an intermediate phenotype.

A typical example is the color of the flower in which R symbolizes the dominant allele for red pigment and r is the recessive allele for no pigment. In incomplete dominance, the heterozygous plant carrying both alleles, Rr, will not be able to produce enough red pigment (since the dominant allele is only partially expressed) and therefore will appear pink.

Synonym: partial dominance.
Compare: complete dominance, codominance. See also: allele.