Question

Imagine that a new species of frog has been discovered in South America. One of its genes controls whether or not it has red spots on its green body. The allele for red spots (R) is completely dominant over the recessive allele (r) for no spots. The frequency of the recessive allele (r) in the population is determined to be 0.2. Assuming the population is in Hardy-Weinberg equilibrium, use the Hardy-Weinberg equations to predict the percent of the next generation of frogs that will have red spots.

Answer 1

A. 96 percent of the population will have red spots.

B. 64 percent of the population will have red spots.

C.80 percent of the population will have red spots.

D. 32 percent of the population will have red spots.

Answer 2

C

Answer 3

Thank you so much :)

Answer 4

No Problem (:

Answer 5

I disagree with Lizzybug. It gives you the frequency of the recessive allele, r, as 0.2. And from that you can easily get the frequency of the dominant allele, R, as 0.8.

But the frequency of the dominant allele does not correspond to the percentage of frogs which exhibit the dominant phenotype. Some of those frogs, the homozygous dominant RR ones, have more than one dominant allele.

The equation for phenotype frequencies is:

\[1 = p^2 + 2pq + q^2\]

Where the p^2 corresponds to the frequency of homozygous dominant frogs and 2pq corresponds to the frequency of phenotypically dominant (i.e., R - red) heterozygous frogs.

So the total number of frogs with the dominant phenotype is the sum of the homozygous dominant frogs and the heterozygous frogs.

\[(0.8)^2 + (2 * 0.8 * 0.2) = 0.96\] or 96%.