Question

In a population of tree frogs, the allele that causes yellow eyes (Y) is dominant over the allele that causes orange eyes (y). If 85% of the frogs have yellow eyes, what is the frequency of the dominant allele?

Answer 1

Hardy Weinburg equilibrium

Answer 2

The Castle Hardy Weinburg equation is\[1 = p^2 + 2pq + q^2\] and you are given that p^2 + 2pq (that is, all the individuals with the dominant phenotype) equals 0.85.

Which gives you q, the frequency of the recessive allele, very easily...\[1 - 0.85 = q^2\]

And once you have q, you can find p, which is what the problem asks for...\[p = 1 - q\]