The following variances were calculated for two traits in a herd of hogs.

  Trait             Vₚ           VG        VA  _
Back fat        30.6        12.2       8.44
Body length  52.4        26.4     11.70

Calculate broad-sense (H²) and narrow-sense (h²) heritabilities for each trait in this herd.

Verified step by step guidance

1. Identify the formulas for broad-sense and narrow-sense heritability: Broad-sense heritability (H^2) is calculated as H^2 = V_G / V_P, and narrow-sense heritability (h^2) is calculated as h^2 = V_A / V_P.
2. For the trait 'Back fat', use the given variances: V_P = 30.6, V_G = 12.2, and V_A = 8.44.
3. Calculate the broad-sense heritability (H^2) for 'Back fat' using the formula H^2 = V_G / V_P.
4. Calculate the narrow-sense heritability (h^2) for 'Back fat' using the formula h^2 = V_A / V_P.
5. Repeat the calculations for the trait 'Body length' using the given variances: V_P = 52.4, V_G = 26.4, and V_A = 11.70.

Key Concepts

Heritability

Heritability is a measure of how much of the variation in a trait can be attributed to genetic differences among individuals in a population. It is expressed as a proportion, ranging from 0 to 1, where 0 indicates no genetic contribution and 1 indicates that all variation is due to genetics. Understanding heritability is crucial for predicting how traits may be passed on to future generations.

Broad-Sense Heritability (H²)

Broad-sense heritability (H²) quantifies the total genetic variance in a trait, including all genetic contributions such as additive, dominance, and interaction effects. It is calculated as the ratio of genetic variance (VG) to phenotypic variance (VP). This measure helps in understanding the overall genetic influence on a trait, but it does not specify the nature of the genetic effects involved.

Narrow-Sense Heritability (h²)

Narrow-sense heritability (h²) focuses specifically on the additive genetic variance (VA) that contributes to the resemblance between parents and offspring. It is calculated as the ratio of additive genetic variance to phenotypic variance (VP). This concept is particularly important for predicting the response to selection in breeding programs, as it reflects the heritable portion of a trait that can be passed on to the next generation.