The hybrid vigor, also known as heterosis or outbreeding enhancement, refers to the phenomenon where the offspring of two different parents exhibit superior traits compared to either of the parents.
Why is hybrid performs better than purebred？
Increased Genetic Diversity: Hybrids result from the combination of genetic material from two distinct parents. This mixing of genes leads to increased genetic diversity in the offspring. Genetic diversity enhances the potential for favorable gene combinations and promotes the expression of beneficial traits. It increases the adaptability and resilience of hybrids to changing environmental conditions.
Masking of Recessive Traits: In many cases, harmful traits are usually recessive, meaning they are expressed only in the homozygous state. When parents with different recessive traits are crossed, the hybrid offspring are usually heterozygous and do not express these harmful recessive traits.
Overdominance: The different alleles may interact each other to enhance expression of specific genes, leading to increased fitness and performance in hybrids. For example, AA and aa are crossed to produce Aa which performs better than its parents. You can consider it as A+a>A or a.
Epistasis: It refers to the interaction between different genes (not alleles), where the effect of one gene depends on the presence of another gene. For example, AAbb and aaBB are crossed to produce AaBb, and A gene enhance the B gene to express a better trait than their parents. You can consider it as A+B>A or B.