Question

Phenotypic variation in tail length of mice has the following components: Additive genetic variance (VA) = 0.5, Dominance genetic variance (VD) = 0.3, Genic interaction variance (VI) = 0.1, Environmental variance (VE) = 0.4, Genetic-environmental interaction variance (VGE) = 0.0.

a. What is the narrow-sense heritability of tail length?

b. What is the broad-sense heritability of tail length?

Answer 1

The narrow-sense heritability of tail length is 0.5, and the broad-sense heritability is 0.9, calculated using the provided genetic and environmental variances.

Step-by-step explanation:

Narrow-sense heritability of tail length is 0.5 (additive genetic variance divided by total phenotypic variance) and broad-sense heritability is 0.9 (sum of all genetic variances divided by total phenotypic variance).

To calculate heritability, we use the variances provided. For narrow-sense heritability (h2), which reflects the contribution of additive genetic variance (VA) to the total phenotypic variance (VP), the formula is h2 = VA/VP.

Accordingly, we first need to calculate the total phenotypic variance which is the sum of all individual variances (VA + VD + VI + VE + VGE). In this case, VP is 0.5 + 0.3 + 0.1 + 0.4 + 0.0 = 1.3. Thus, h2 = 0.5 / 1.3.

For broad-sense heritability (H2), which includes all genetic variance components (VA, VD, VI), we add these together and divide by the total phenotypic variance. H2 = (VA + VD + VI)/VP. So, H2 = (0.5 + 0.3 + 0.1) / 1.3.