1. Given a population with pa = 0.70 and qb
= 0.30, answer the following questions:
a) If a mutates to b at a rate
of
4 x 10-5, estimate p in 100 generations.
b) If m = 0.12 from a population where p =
0.60,
estimate delta-p.
2. In the bacterium E. coli, the rate of
mutation from
histidineindependence (his+) to histidine requirement (his-)
is 2 x 10-6, while the rate of reverse mutation is 4 x 10-8.
Predict p+, the equilibrium frequency of the independence
gene.
3. Assume that the rate of mutation from a to b
at
a certain locus in Drosophila melanogaster is 2 x 10-5,
while the rate of reverse mutation b to a is 6 x 10-7.
Predict pa. Is the calculation of mutation equilibrium
frequency
different for diploid and haploid organisms?
4. Assume that at a certain locus the mutation rate of a
to b is 10-6 and that there is no back
mutation.
From a starting frequency pa = 1.0, predict pa
after
10, 1000, and 100,000 generations.
5. The selection coefficient against a deleterious
recessive mutation in mice is known to be s = 0.9. If we observe
a frequency of
0.9996 of normal individuals in a population, what is the mutation
rate?
6. Although the autosomal recessive disease phenylketonuria
can become severely debilitating, dietary
precautions may be taken if detection is early. Human populations
were sampled from an isolated region of West Virginia and from New York
City.
The frequency of the PKU gene was found to be 1 x 10-5 in
West
Virginia and 5 x 10-5 in New York. How much stronger
is
selection in West Virginia?
7. Assume that the mutation rate to the lethal recessive
Tay-Sachs gene is 1 x 10-5. What is its equilibrium
frequency?
8. A population geneticist estimated the frequency of
allele a in annual population #1 to be 0.90, and in population
#2 to be 0.65.
He returned the following year and found pa to be 0.88 in
population
#1. What migration coefficient does this suggest?
9. If the size of population #1 is 600, estimate its
number of immigrants per generation.
Answers:
1a) 0.697, 1b) -0.012
2) p+ = 0.02, 3) pa =
0.03,
No difference in calculations for haploids and diploids.
4) p10 = 0.99999, p100 = 0.999, p100,000
= 0.905.
5) 3.6 x 10-4
6) 25 times
7) pTS = 0.0032.
8) m = 0.08, 9) 48 migrants/generation