Evolutionary Theory and Dominance

Evolutionary Theory and Dominance

Definition of Dominance

• Dominance refers to the phenomenon where one allele (a variant of a gene) has a greater effect on the phenotype than another allele.
• In a heterozygous individual, the dominant allele will be expressed in the phenotype, while the recessive allele will not.

Evolutionary Significance of Dominance

• Dominance can influence the evolution of populations by affecting the frequency of alleles.
• Dominant alleles can spread quickly through a population, even if they are not the most common allele.
• Recessive alleles can be maintained in a population at a low frequency, even if they are deleterious.

Types of Dominance

• Complete Dominance: One allele completely masks the effect of the other allele.
• Incomplete Dominance: The effect of one allele is not completely masked by the other allele, resulting in a intermediate phenotype.
• Co-Dominance: Both alleles have an equal effect on the phenotype.

Mechanisms of Dominance

• Genetic Dominance: One allele is expressed more strongly due to its genetic makeup.
• Epigenetic Dominance: One allele is expressed more strongly due to environmental or epigenetic factors.

Examples of Dominance

• Sickle Cell Anemia: The HbS allele is recessive to the normal HbA allele, but is dominant in its effect on the phenotype.
• Flower Color: In some plants, the red allele is dominant to the white allele, resulting in red flowers.

Importance of Dominance in Evolution

• Dominance can influence the evolution of populations by affecting the frequency of alleles.
• Understanding dominance is important for predicting the outcomes of breeding programs and genetic engineering.
• Dominance can also affect the evolution of disease resistance and susceptibility.

Definition and Concept of Dominance

• Dominance refers to the phenomenon where one allele has a greater effect on the phenotype than another allele.
• In a heterozygous individual, the dominant allele is expressed in the phenotype, while the recessive allele is not.

Evolutionary Significance of Dominance

• Dominance influences the evolution of populations by affecting the frequency of alleles.
• Dominant alleles can spread quickly through a population, even if they are not the most common allele.
• Recessive alleles can be maintained in a population at a low frequency, even if they are deleterious.

Types of Dominance

• Complete Dominance: One allele completely masks the effect of the other allele.
• Incomplete Dominance: The effect of one allele is not completely masked by the other allele, resulting in an intermediate phenotype.
• Co-Dominance: Both alleles have an equal effect on the phenotype.

Mechanisms of Dominance

• Genetic Dominance: One allele is expressed more strongly due to its genetic makeup.
• Epigenetic Dominance: One allele is expressed more strongly due to environmental or epigenetic factors.

Examples of Dominance

• Sickle Cell Anemia: The HbS allele is recessive to the normal HbA allele, but is dominant in its effect on the phenotype.
• Flower Color: In some plants, the red allele is dominant to the white allele, resulting in red flowers.

Importance of Dominance in Evolution

• Dominance influences the evolution of populations by affecting the frequency of alleles.
• Understanding dominance is important for predicting the outcomes of breeding programs and genetic engineering.
• Dominance can also affect the evolution of disease resistance and susceptibility.