Question

The allele for black spots is dominant over the allele for brown spots in lady beetles. Of 274 lady beetles observed, 188 had black spots and 86 had brown spots. If this population of lady beetles is in Hardy-Weinberg equilibrium for the spot locus, answer the following questions:

To receive full marks, please show your work and explain your reasoning.

(a) What is the frequency of the allele for brown spots? (1.25 marks)

(b) What is the frequency of the allele for black spots? (1.25 marks)

(c) How many of the lady beetles in this population are likely to be heterozygous at the spot locus?

Answer 1

In this case, we will use the Hardy Weinberg assumption where: p = Dominant allele = black spots q = Recessive allele = brown spots p + q = 1 p2 = frequency of homozygous dominant q2 = frequency of homozygous recessive 2pq = frequency of heterozygous 2pq = frequency of heterozygous Frequency of heterozygous = 2 x 0.55 x 0.45 = 0.495 Number of heterozygous individuals = 274 x 0.495 = Around 136 individuals 86 Frequency of q2 = = 0.31 274 Frequency of q = 0.31 = 0.55 p + 9 = 1 p = 1-0.55 = 0.45 (a) What is the frequency of the allele for brown spots? 0.55 (b) What is the frequency of the allele for black spots? 0.45