A hypothetical study investigated the vitamin A content and the cholesterol content of eggs from a large population of chickens. The following variances (V) were calculated.

Calculate the narrow-sense heritability (h²) for both traits.

Verified step by step guidance

1. Understand that narrow-sense heritability (h²) is the proportion of the total phenotypic variance (V_P) that is due to additive genetic variance (V_A). The formula is: \(h^{2} = \frac{V_{A}}{V_{P}}\).
2. Identify the values for each trait from the table: for Vitamin A, V_P = 125.5 and V_A = 12.0; for Cholesterol, V_P = 862.0 and V_A = 192.1.
3. Apply the formula for Vitamin A: substitute V_A = 12.0 and V_P = 125.5 into \(h^{2} = \frac{V_{A}}{V_{P}}\) to express the heritability calculation.
4. Apply the formula for Cholesterol: substitute V_A = 192.1 and V_P = 862.0 into \(h^{2} = \frac{V_{A}}{V_{P}}\) to express the heritability calculation.
5. Interpret the results by understanding that higher h² values indicate a greater proportion of phenotypic variance is due to additive genetic factors, which implies stronger potential for response to selection.

Key Concepts

Phenotypic Variance (V_P)

Phenotypic variance represents the total observed variation in a trait within a population. It includes genetic variance (additive, dominance, etc.) and environmental variance. Understanding V_P is essential because it forms the denominator in heritability calculations, reflecting all sources of variation affecting the trait.

Additive Genetic Variance (V_A)

Additive genetic variance is the portion of genetic variance attributed to the additive effects of alleles. It is crucial for predicting response to selection because it reflects the heritable component passed from parents to offspring. Narrow-sense heritability is calculated using V_A relative to total phenotypic variance.

Narrow-Sense Heritability (h²)

Narrow-sense heritability (h²) quantifies the proportion of phenotypic variance due to additive genetic variance (h² = V_A / V_P). It measures the potential for a trait to respond to selection and is key in breeding and evolutionary studies. Calculating h² requires knowledge of both V_A and V_P.