How does additive genetic variation help animal breeders make permanent genetic gains?

In animal breeding, additive genetic variation is a crucial component for long-term improvement because the effect of each allele at a specific locus simply adds to the effects of other alleles at that same location. Unlike dominance or epistatic variations, which are more complex to identify or control, additive effects are relatively straightforward to utilize in selective breeding programs.1

Genetic gains derived from additive genetic effects are considered permanent and cumulative, meaning they build upon one another from one generation to the next. Because heritability is defined as the proportion of additive genetic variation to total variation, it serves as a primary guide for breeders; when heritability is high, breeders can effectively use an individual's own trait records to drive rapid genetic change.12

Ultimately, the rate of genetic gain is influenced by the standard deviation of this additive genetic variation within a population, which breeders balance alongside selection intensity, accuracy, and the generation interval to achieve consistent progress.3