A population of beavers has 135 individuals that are homozygous for one allele, 230 that are heterozygous, and 135 that are homozygous for the other allele.Compared with Hardy-Weinberg expectations, this population has _______ too _____ heterozygotes.
A) 10; many
B) 10; few
C) 20; many
D) 20; few
E) 50; many

Question

Quizplus · Accepted Answer

The Hardy-Weinberg equation predicts that the proportion of heterozygotes in a population will be 2pq, where p = frequency of one allele and q = frequency of the other allele. In this case, there are a total of 500 beavers in the population, so the frequency of the homozygous dominant allele (p) is 135/500 = 0.27 and the frequency of the homozygous recessive allele (q) is also 0.27. Therefore, the frequency of the heterozygous individuals should be 2(0.27)(0.73) = 0.3942, or approximately 39%. However, there are actually 230/500 = 0.46 or 46% heterozygotes, which is higher than expected. The population has 20 more heterozygotes than expected, which is not a large deviation from expectation. Therefore, the correct answer is D: 20; few.

A Population of Beavers Has 135 Individuals That Are Homozygous