In a diploid population, initial allele frequencies are $p = 0.6$ (allele A) and $q = 0.4$ (allele a). Fitness values are $w_{AA} = 1.0$ , $w_{A a} = 0.9$ , $w_{aa} = 0.7$ . Find the allele frequency of $A$ after one generation of selection.

medium 3 marks Class 12 · Biology · Organisms and Populations

Answer

0.876

The correct answer is 0.876 — Therefore the new allele frequency of $A$ is approximately 0.876.

Step-by-step solution

Calculate mean fitness: $\overline{w} = p^{2} w_{AA} + 2 pq, w_{A a} + q^{2} w_{aa} = 0.36 + 0.432 + 0.112 = 0.904$ .
Compute the numerator for $p^{'}$ : $p^{2} w_{AA} + pq, w_{A a} = 0.36 + 0.432 = 0.792$ .
Divide by mean fitness: $p^{'} = \frac{0.792}{0.904} \approx 0.876$ .
Therefore the new allele frequency of $A$ is approximately 0.876.

Common mistake: Using wrong formula for mean fitness or numerator

Concept tested: Allele frequency after selection