Question

Imagine if we tested genotype frequencies in our hypothetical population of 145 individuals where p=.59 and q=.41, and found the following to be true of the population: 35 individuals had the AA genotype, 100 had the Aa genotype, and 10 had the aa genotype. What might we infer about the adaptive value of the heterogenous genotype?

A. It has no adaptive value.

B. It has been adaptive and subject to selective pressures.

C. It has been selected against.

D. Its frequency is likely due to genetic drift.

Answer 1

Given, p = 0.59 and q = 0.41.

Observed numbers in each class: :35 individuals had the AA genotype, 100 had the Aa genotype, and 10 had the aa genotype.

Let us calculate expected number of heterozygous individual, Aa, using the formula 2pq×N, where N is the population size.

=2×0.59×0.41×145

=70.15

Thus, we expect~70 Aa individuals, but there are 100 such individuals in the population. Thus, heterozygous has some adaptive value and it has been selected for, as its frequency is more than expected.

Genetic drift generally reduces heterozygosity in a population, and hence we would have observed a lower frequency of Aa individuals than expected, which isn't the case.

Most appropriate choice should be:

(B)It has been adaptive and subject to selective pressures.