How do BV and EBV differ in terms of the genetic loci they summarize?

How do BV and EBV differ in terms of the genetic loci they summarize?

• A. BV is associated with a single locus; EBV involves many loci
• B. BV and EBV are equivalent concepts
• C. EBV involves environmental variance
• D. BV is not used in breeding

Answer: (A)

The key idea is that both breeding value and estimated breeding value reflect additive genetic contributions from many genes, not just one. The true breeding value of an individual is the sum of the average effects of alleles across the genome—the cumulative additive effect from all loci that influence the trait. In almost all quantitative traits, many loci contribute small amounts, so BV represents a polygenic additive value rather than a single-locus effect. Estimated breeding value, on the other hand, is our statistical prediction of that true BV. It uses available data—phenotypes, genealogical relationships, and often marker information—to infer the additive genetic value. Because it’s based on data, EBV is an estimate and its accuracy improves with more information. Both concepts summarize additive effects across multiple loci; EBV just provides an empirical estimate of BV rather than a fixed, known quantity. So, the idea that a breeding value is tied to a single locus isn’t accurate for typical polygenic traits, and EBV isn’t defined simply by environmental variance. BV and EBV both reflect many loci, with EBV being the data-driven estimate of BV.

The key idea is that both breeding value and estimated breeding value reflect additive genetic contributions from many genes, not just one. The true breeding value of an individual is the sum of the average effects of alleles across the genome—the cumulative additive effect from all loci that influence the trait. In almost all quantitative traits, many loci contribute small amounts, so BV represents a polygenic additive value rather than a single-locus effect.

Estimated breeding value, on the other hand, is our statistical prediction of that true BV. It uses available data—phenotypes, genealogical relationships, and often marker information—to infer the additive genetic value. Because it’s based on data, EBV is an estimate and its accuracy improves with more information. Both concepts summarize additive effects across multiple loci; EBV just provides an empirical estimate of BV rather than a fixed, known quantity.

So, the idea that a breeding value is tied to a single locus isn’t accurate for typical polygenic traits, and EBV isn’t defined simply by environmental variance. BV and EBV both reflect many loci, with EBV being the data-driven estimate of BV.