If Hardy-Weinberg conditions exist, what will happen to the frequency of a dominant allele over time?

Question

a.) the frequency will increase

b.) the frequency will decrease

c.) the frequency will remain the same

d.) the frequency will double with each generation

e.) it is impossible to predict the frequency

Answer 1

In short the Hardy-Weinberg principle states that genotype frequencies in a population remain constant from generation to generation in the absence of other evolutionary influences, like natural selection, mutation, etc.

This can be shown mathematically, based on totally random pairings (the absence of any outside evolutionary or selection bias).

Contact me if you'd like me to show you the math - it's pretty simple, but impossible to explain properly here.

It's based on the binomial expansion of p + q = 1, p² + 2pq + q².

Answer 2

c.) the frequency will remain the same

If the conditions of Hardy Weinberg are met then there will be a constant frequency of the alleles in a population. The conditions that need to be met are no mutation or change in the DNA, no migration of new alleles into the population, a large population size, random mating (no sexual selection), and no natural selection.

In most naturally occurring populations Hardy Weinberg is not observed because most of those conditions are not met. This can skew the frequency of alleles towards the more beneficial traits.