Which components comprise genetic value G?

Which components comprise genetic value G?

• A. Environmental effects
• B. Additive (A), Dominance (D), and Epistasis (I)
• C. Additive only
• D. Dominance and Epistasis only

Answer: (B)

Genetic value G is the total genetic contribution to a phenotype, including all gene actions: additive effects (A), dominance deviations (D) from interactions of alleles at the same locus, and epistasis (I) from interactions among different loci. Additive effects represent the average effect of substituting alleles and are what is most predictably passed to offspring, which is why breeders often emphasize additive value. The non-additive parts—dominance and epistasis—shape the phenotype but aren’t simply transmitted as additive contributions. Environmental effects don’t belong to G since they arise from outside the genotype. So, the full genetic value is G = A + D + I.

Genetic value G is the total genetic contribution to a phenotype, including all gene actions: additive effects (A), dominance deviations (D) from interactions of alleles at the same locus, and epistasis (I) from interactions among different loci. Additive effects represent the average effect of substituting alleles and are what is most predictably passed to offspring, which is why breeders often emphasize additive value. The non-additive parts—dominance and epistasis—shape the phenotype but aren’t simply transmitted as additive contributions. Environmental effects don’t belong to G since they arise from outside the genotype. So, the full genetic value is G = A + D + I.