Question

1. Walking through the forest, you find a large population of toadstools. From your extensive knowledge of the kingdom fungi, you know that the allele for being spotted (S) is dominant over the allele for being plain (s). In this population of 1007, you find 14 toadstools that are not spotted. What are the allele frequencies? In a different forest, you find a somewhat smaller population of 549. Through genetic testing, you determine that there are 308 homozygous spotted, 206 heterozygous, and 34 homozygous plain toadstools. Is this what you expected? If not, what are the allele frequencies of this population?

Answer 1

Answer:

No, observed and expected frequencies are different.

Observed frequencies: p2 = 0.56 , 2pq = 0.375, q2 = 0.062

Expected frequencies: p2 = 0.774 , 2pq = 0.211, q2 = 0.014

Explanation:

Given frequency of recessive genotype (q2)= 14/ 1006 = 0.0139

Frequency of recessive allele s (q) = square root of 0.0139 = 0.12

Frequency of dominant allele S (p) = 1-q = 1-0.12 = 0.88

Expected frequency of homozygous recessive genotype = 0.12 x 0.12 = 0.014

Expected frequency of homozygous dominant genotype = 0.88 x 0.88 = 0.774

Expected frequency of heterozygous dominant genotype = 2pq = 2 x 0.88 x 0.12 = 0.211

Observed frequencies in population 2

Observed frequency of homozygous dominant genotype = 308 / 549 =0.56

Observed frequency of heterozygous dominant genotype = 206 / 549 =0.375

Observed frequency of homozygous recessive genotype = 34 / 549 =0.062

Observed frequencies do not match with expected frequencies.