Suppose a population of flour beetles has 1,000 individuals.Normally the beetles are red; however, this population is polymorphic for a mutant autosomal body color, black, designated by bb.Red is dominant to black, so BB and Bb genotypes result in red beetles.Assume the population is at Hardy-Weinberg equilibrium, with equal frequencies of the two alleles.What would be the expected frequencies of the red and black phenotypes?
A) 0.5 red and 0.5 black
B) 0.75 red and 0.25 black
C) 0.25 red and 0.75 black
D) All red
E) More information is required to answer this question.

Question

Quizplus · Accepted Answer

At Hardy-Weinberg equilibrium, the expected genotype frequencies are p² for BB, 2pq for Bb, and q² for bb, where p and q are the frequencies of the dominant (red) and recessive (black) alleles, respectively. Since the problem states that there are equal frequencies of the two alleles, p and q are both 0.5. Thus, the expected genotype frequencies are 0.25 for BB, 0.5 for Bb, and 0.25 for bb. To find the expected phenotype frequencies, we combine the frequencies of the genotypes that produce each phenotype. Since BB and Bb both produce the red phenotype, the expected frequency of red beetles is 0.25 + 0.5 = 0.75. The expected frequency of black beetles is q² = 0.25. Therefore, the answer is B.

Suppose a Population of Flour Beetles Has 1,000 Individuals