Exam 2 practice problems #2
1.
A gene has two alleles b and B. The allele B has a frequency of 0.8 and b has a frequency of 0.2.
Fitness values for the genotypes are as follow:
Wbb = 5
wbB = 4
wBB = 3.
Calculate the average fitness of the population (wbar). [wbar means w with a line over the top. I can’t write
that so I’m using wbar instead].
2.
A gene has two alleles d and D. The frequency of d is 0.1 and the frequency of D is 0.9. The
genotype fitness values are as follow:
wdd = 9
wdD = 6
wDD = 3
Given that the average fitness of the population (wbar) is 3.6 calculate (1) the average excess of fitness
(ad) for the allele d
(2) calculate delta q the change in the frequency of d from one generation to the next
and (3) calculate the frequency of the allele d in the next generation
3. A gene has two alleles d and D. The genotype fitness are as follow:
wdd = 4
wdD = 1
wDD = 1
The frequency of allele D is 0.9 and the frequency of allele d is 0.1.
(a) Calculate the average fitness of the population (wbar )
(b) Calculate the expected frequency of the allele d in the next generation (t+1)
4.
Using the same values as in question 3 for genotype fitnesses repeat the same calculations as
for question 3, but this time for starting allele frequencies of D = 0.5 and d =0.5.
wdd = 4
wdD = 1
wDD = 1
(a)Calculate the average fitness of the population (wbar )
(b) Calculate the expected frequency of the allele d in the next generation (t+1)
(c) Explain why the frequency of allele d increases much more in generation t+1 than it did in
question 3.