What is incomplete dominance?

Incomplete dominance is a genetic phenomenon where the resultant phenotype of a heterozygous individual is a blend or intermediate of the phenotypes associated with the two different alleles present. This means that neither allele is completely dominant over the other, leading to a situation where the physical expression is not simply one trait overshadowing another, but rather a combination that creates a unique phenotype.

For instance, if you have a flower species where one allele codes for red flowers and another codes for white flowers, in an individual that is heterozygous for these alleles, you might see pink flowers as a result. This illustrates that the traits do not compete for dominance but instead contribute to a new expression.

This concept contrasts with complete dominance, where one allele completely masks the presence of another, resulting in only the dominant phenotype being expressed. Additionally, while both alleles expressing equally might sound similar, that describes codominance rather than incomplete dominance. Furthermore, sex-linked traits refer to genes located on sex chromosomes, leading to different patterns of inheritance that do not relate to the concept of dominance being incomplete.