Difference Between Incomplete Dominance and Codominance

Difference between Incomplete Dominance and Codominance: Incomplete dominance and co-dominance are two exceptions to Mendel’s law of dominance. Incomplete dominance involves a blending of traits in heterozygous individuals, while codominance results in both alleles being fully expressed simultaneously in heterozygotes.

The incomplete dominance was discovered by Carl Correns in the plant Mirabilis jalapa whereas codominance was discovered by Morgan in chickens. This article will discuss the key differences between incomplete dominance and codominance along with some similarities.

What is Incomplete Dominance?

Incomplete dominance occurs when neither of two alleles of a gene completely dominates the other, resulting in a blend of traits. In other words, the dominant allele is unable to mask the effects of the recessive allele, and hence the resulting phenotype is a blend of both the alleles. It can be also called partial dominance as both alleles are partially dominant and this characteristic is an exception to Mendel’s law of dominance.

Incomplete Dominance Example: When a red flower plant (RR) is crossed with a white flower plant (WW), their offspring (RW) may display a pink color, showing an intermediate trait between red and white.

Read for More Information: Incomplete Dominance & Mendel’s Experiment

What is Co-Dominance?

Co-dominance is a genetic concept where both alleles in a heterozygous individual are fully expressed, resulting in a phenotype that shows characteristics of both alleles. It means that no allele masks the effect of the other allele and both alleles act as dominant. The phenoype shows the traits of both alleles.

Co dominance Example: In snapdragons, a cross between red-flowered (RR) and white-flowered (WW) plants results in offspring with both red and white flowers (RW), demonstrating co-dominance

Read for More Information: Co-Dominance

Difference Between Incomplete Dominance and Co-Dominance

The incomplete dominance vs co-dominance is given below in a tabular form:

Characteristics	Incomplete Dominance	Co-dominance
Definition	In a heterozygous pair of alleles, the dominant allele does not mask the expression of the recessive allele.	In a heterozygous pair of alleles, both genes lose their dominant and recessive characteristic.
Form of expression	Both the alleles are expressed as an intermediate phenotype.	Both the alleles get expressed in the phenotype.
Expression in Offspring	They are expressed in a mixed form in the offspring.	They are expressed independently in the offspring.
Characteristic of offspring	A hybrid offspring is formed.	No hybrid offspring are formed.
Extent of expression	Sometimes one allele might be slightly more expressed than the other.	Both alleles are expressed equally.
Interaction between the alleles	One allele is incompletely dominant over the other.	No allele is dominant or recessive over the other.
Examples	Formation of pink-colored flowers in Mirabilis jalapa and Antirrhinum majus.	ABO blood grouping in humans, and coat color in chickens.

Incomplete Dominance and Codominance Similarities

Some of the similarities between incomplete dominance and codominace is given below:

• Non-Mendelian Inheritance: Neither incomplete dominance nor codominance follow the simple 3:1 phenotypic ratio predicted by Mendel’s laws.
• Allelic Interaction: Both involve interactions between alleles of the same gene, leading to deviations from complete dominance.
• Dominant Traits: In both cases, at least one allele is considered dominant because it is expressed when paired with a recessive allele.

Conclusion – Difference Between Incomplete Dominance and Codominance

In conclusion, incomplete dominance and co-dominance are exceptions to Mendel’s law of dominance, each revealing unique patterns of allele expression. The difference between incomplete dominance and co dominance lies in how the two alleles interact with one another. In incomplete dominance, traits blend in heterozygotes, while in co-dominance, both alleles express fully. These concepts challenge Mendel’s laws, offering insights into complex genetic interactions.

Difference Between Related Links

Difference Between Homozygous And Heterozygous	Difference Between Protostomes and Deuterostomes
Difference Between Monohybrid And Dihybrid	Difference Between Primary And Secondary Succession
Difference Between Dominant and Recessive Traits	Difference Between Monocotyledon And Dicotyledon
Difference Between Phenotype and Genotype Ratio	Difference Between Cross-Pollination And Self Pollination
Difference Between Gene And Allele	Difference Between Chromosome and Gene

FAQs on Difference Between Incomplete Dominance and Codominance

What is the Phenotypic Ratio of F2 Generation in Incomplete Dominance?

Instead of the usual 3:1, the phenotypic ratio of F2 generation in incomplete dominance is 1:2:1.

In ABO Which Alleles Show the Co-Dominance?

In ABO grouping allele A (A blood group) and allele B (B blood group) shows co-dominance resulting in the formation of AB alleles (AB blood group).

What Type of Relationship does Allele O Show with Allele A and Allele B?

Allele O is recessive to allele A and allele B, so it gets dominated in the presence of A or B.

Why Allele O is Recessive to Allele A and Allele B?

Because allele O lacks the protein that is responsible to form antigen O whereas allele A and allele B have the proteins to produce the antigen A and B respectively. These antigens give the group A, B, and O.

What is the Difference Between Incomplete Dominance and Codominance?

The difference between incomplete dominance and codominance lies in how alleles are expressed in heterozygous individuals. In incomplete dominance, alleles blend to produce an intermediate phenotype, while in codominance, both alleles are fully expressed simultaneously showing characteristics of both alleles.