Question

In the Eruopean Land snail, multipe alleles at a single locus determine shell color. The allele for brown (S^B) is dominant to the allele for pink (S^P) and to the allele for yellow (S^Y). PInk is recessive to brown, but dominant to yellow.

a. In a population of 1000 snails, 160 are yellow. Assuming the populations is Hardy-Weinberg Equilibrium, calculate th frequency of the yellow allele,

r = f(S^Y) = ?

b. Given that p = f(S^B) = 1. Calculate the frequency of each of the following. Show work please

f (S^BS^B) = ?

f (S^BS^P) =?

f (S^BS^Y) = ?

f (S^PS^P) = ?

f(S^PS^Y) = ?

f (S^YS^Y) = ?

c. Give the phenotypic frequencies and show all work please

f(brown) = ?

f(pink) = ?

f(yellow) = ?

Answer 1

a. In a population of 1000 snails, 160 are yellow. Assuming the populations is Hardy-Weinberg Equilibrium, calculate
the frequency of the yellow allele (recessive) is r = f(SY) = 160/1000 = 0.16 (homozygous recessive)
therefore, the frequency of the allele for yellow shells q = 0.4, which means p=0.6.

b. Frequency of SBSB = 0.6*0.6 = 0.36
Frequency of SBSP = 0.6*0.4 = 0.24
Frequency of SBSY = 2*0.6*0.4 = 0.4