Genetics 303
Fourth exam—take home 2019
Answer on SEPARATE paper, show all work, and be neat in the reporting of answers. It is easier to grade if you try to
keep the questions in sequence. STAPLE YOUR RESULTS!
1. In a human population, the genotype frequencies at one locus are 0.75 AA, 0.20 Aa, and 0.05 aa. What is the frequency
of the A allele [f(A)] and a allele [f(a)] for the population? Are they in Hardy-Weinberg equilibrium? (5 pts)
2. Calculate the number of heterozygotes in a population with p = 0.6 and q = 0.4 (at time = 0). After 4 generations of
inbreeding between siblings (F = 0.25) in a population of 650. (6 pts)
3. Human albinism is an autosomal recessive trait. Suppose that you find a village in the Andes where 8/1000 of the
population is albino. If the population size was 1600 and the population is in Hardy-Weinberg equilibrium with
respect to this trait, how many individuals are expected to be carriers (heterozygotes)? (5pts)
4. A boatload of 400 Swedish tourists, all of whom bear the MM blood group genotype, are marooned on Haldane Island,
where they are met by an population of Islanders totaling 1000, all bearing blood group NN genotype. In time, the
castaways become integrated into Island society. Assuming random mating, no mutation, no selection (based on
blood group), and no genetic drift, what would you expect the blood group distribution to be among 320 progeny of
the new Haldane Island population? (5 pts)
5. You identify a population of mice (Peromyscus maniculatus) on an island. Their coat color is controlled by a single
gene: BB mice are black, Bb mice are gray, and bb mice are white. You take a census of the population and record
the following numbers of mice:
Black 1156
Gray 408
White 36
(a) What are the frequencies of the two alleles? (4 pts)
(b) What are the Hardy-Weinberg equilibrium frequencies for these three phenotypes? (4 pts)
(c) A heat wave hits the island. All mice with black fur die from heat stroke, but the other mice survive. What are the new
allele frequencies for the population? (4 pts)
(d) If the population suffers no further cataclysms after the heat wave, and the surviving animals mate randomly, what will
be the frequency of mice with black fur in the next generation? (4 pts)
(e) If the climate is altered permanently, so that mice with black fur die before reproducing, which following statement is
correct? (5 pts)
(1) At Hardy-Weinberg equilibrium, f(B) will equal 0.135.
(2) The fitness of mice with gray fur (ωBb) must be equal to 0.5.
(3) The fitness of mice with black fur (ωBB) is 0.
(4) The B allele will disappear from the population in one generation.
(5) The B allele will disappear from the population in two generations.
6. Which of the following are requirements for evolution by natural selection? Explain your answer. (8 pts)
I Environmental change
II Differential survival and reproduction
III Heritability of phenotypic variation
IV Variation in phenotype
V Sexual reproduction
A) II, III, V
B) II, III, IV
C) I, II, IV
D) III, IV, V
E) II, IV, V
7. Which of the following processes is the source of genetic variation within populations? (8 pts)
A) Reproductive Isolation
B) Mutation
C) Selection
D) Asexual reproduction
E) Genetic drift
Explain your answer including a description of the impact of each on genetic variation.
8. If the population (17,377 in 2018) of folks in Perry, GA, had an f(a) = 0.2 and folks in Valdosta, GA, has a f(a) = 0.6,
then how many people from Valdosta, GA, would have to migrate to Perry to increase the population to
approximately f(a) = 0.3? (5 pts, remember, you can’t have fractional people)
9. What is the Ne of a population with the following annual censuses, [note: the drop in size due to 2010 and 2011 being
extreme drought years]? (5 pts)
2008: 9730
2009: 8810
2010: 3653
2011: 420
2012: 94
2013: 1560
2014: 5650
2015: 8700
2016: 9700
2017: 12110
2018: 15060
2019: 30789
10. Consider the following populations that have the genotypes shown in the following table:
Population AA Aa aa
1 1.0 0.0 0.0
2 0.0 1.0 0.0
3 0.25 0.50 0.25
4 0.25 0.25 0.50
5 0.333 0.333 0.333
6 0.0225 0.255 0.7225
7 0.5929 0.3542 0.0529
8 0.9604 0.0392 0.0004
a. What are p and q for each population? (4 pts)
b. Which of the populations are in Hardy-Weinberg equilibrium? (4 pts)
c. Populations 1 and 2 have a tree fall across their islands so that individuals can cross. If equal numbers of the
individuals occur on each island, what is the new population’s allele frequencies and genotype frequencies
after one generation of random mating? (6 pts)
d. In population 3, the a allele is less fit than the A allele, and the A allele is incompletely dominant. The result
is that AA is perfectly fit (= 1.0), Aa has a fitness of 0.8, and aa has a fitness of 0.6. With no mutation or
migration, graph the allele frequency of the a allele after 10 generations under selection (e.g., Time 0 = q
above, Time 1 = first generation after selection) (8 pts)
e. In population 8, the population size gets radically reduced to 50 individuals, total. What is the most likely
fate of the “a” allele, and what genetic principle would lead you to believe that the case? (4 pts)
11. You digest a linear piece of DNA with two restriction enzymes, BamH1 & Sma1, and get the following sized
fragments (in kb [kilobases]) (10 pts):
BamH1 Xho1 BamH1 & Xho1
10 kb 12 kb 8 kb
6 kb 8 kb 6 kb
4 kb 4 kb
2 kb
Draw the appropriate restriction fragment map based on this data labeling all restriction sites
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