Two populations of Galapagos lava lizards living on different islands show an allele at a frequency of p = 0.2 and p = 0.6, respectively, at a locus with two neutral alleles. Assuming that both populations are in Hardy-Weinberg equilibrium and have the same size, what would be the heterozygosity at that locus in a population formed by pooling the two lizard populations?

a) 0.36

b) 0.4

c) 0.44

d) 0.48

e) 0.52

B - 0.4

Explanation:

Using the Hardy-Weinberg equation-

p^{2}+2pq+q^{2} = 1

First population, where p = 0.2, q = 1 - 0.2, therefore, q = 0.8

Inserting the values into the equation for the first population-

(0.2 x 0.2) + 2pq + (0.8 x 0.8) = 1

0.04 + 0.64 + 2pq = 1

0.68 + 2pq = 1

2pq = 1 - 0.68

pq = 0.32/2

pq = 0.16

repeating equation for second population, where p = 0.6, q = 1 - 0.6, therefore, q = 0.4

Inserting values ...

(0.6 x 0.6) + 2pq + (0.4 x 0.4) = 1

0.36 + 0.16 + 2pq = 1

0.52 + 2pq = 1

2pq = 1 - 0.52

pq = 0.48/2

pq = 0.24

Adding the two results to determine the heterozygosity of the locus of the combined population, would give-

0.16 + 0.24 = 0.4