Suppose that in a population of Peacocks the phenotypic variance for tail length

Question

Suppose that in a population of Peacocks the phenotypic variance for tail length is 2.5 and the slope of the father–offspring regression for this trait is 0.2.From a long-term captive population you also have data from a line of completely inbred individuals. In this line the phenotypic variance among individuals is 0.50. Assume that there are no shared environmental effects (Ves) and no epistatic variance (VI) for this trait. (Note that these questions are not given in the order that you need to solve them)

a.) What is the total genetic variance for tail length?

b.) What is the additive genetic variance?

c.) What is the dominance genetic variance?

d.) What is the environmental variance?

e.) What is the narrow-sense heritability (h2)?

f.) What is the expected phenotypic covariance among full-sibs?

Explanation / Answer

a to f solution..........

(H2) broad-sense heritability of tail length reflects all the genetic contributions to a population's phenotypic variance including additive, dominant, genetic interactions and environmental effects.

H2 = 0.3 + 0.2 + 0.1 + 0.2 = 0.8

A particularly important component of the genetic variance is the additive variance, Var(A), which is the variance due to the average effects (additive effects) of the alleles. Since each parent passes a single allele per locus to each offspring, parent-offspring resemblance depends upon the average effect of single alleles. Additive variance represents, therefore, the genetic component of variance responsible for parent-offspring resemblance. The additive genetic portion of the phenotypic variance is known as Narrow-sense heritability (h2).

h2 = 0.3

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