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Name (2 points if printed in pencil)____________________________Biology 425 Exam 1A
Please answer the following multiple choice questions (2 pts each). Note: there are numerous
extra points built into this exam, so you can miss quite a few questions and still score 100% (in
other words, you probably will end up doing better than you think you are doing!).
1. From a population standpoint, what are distinctions between the AIDS pandemic in Africa and
the rest of the world? a) the incidence of AIDS in Africa is higher b) more men than women are
afflicted in Africa
c) a+b
d) neither a nor b
2. Which cells in the human immune system have the shortest lifespan?
a) naïve T cells
b) memory T cells
c) effector cells
3. Do individuals evolve?
a) yes b) no
4. For the Eda rescue experiment that created transgenic sticklebacks, what was the phenotype of
the parents? a) both complete
b) both low c) one complete, one low
5. Bell’s experiments on sticklebacks in Loberg Lake showed
a) a rapid increase in the frequency of the complete-plated morph b) evidence for a two-year
lifecycle
c) a+b
d) neither a nor b
6. Circle the graph that best shows the molecular clock assumption?
Number of
Base pair
substitutions
(Y axis for
all four graphs)
Amount of time elapsed since genetic divergence
7. According to Gould, what do orchids have in common with the Panda’s thumb?
a) adaptation usual leads to perfect solutions to problems b) natural selection operates on
existing variation
c) natural selection can operate on structures that originally served very
different functions
d) a+b
e) a+c
f) b+c
g) all are true
8. Which of the following is true about bootstrapping a sequence of DNA that is 500 bases long?
a) Each position (or site) is randomly chosen for each data set
b) it is unlikely that the actual
DNA sequence will be one of the data sets used in the bootstrap analysis
c) bootstrapping is used to determine which tree is most parsimonious
d) a+b
e) a+c
f) b+c
g) all are true
9. A purine replaces a pyrimidine in a a) deletion
e) duplication
1
b) indel
c) transition
d) transversion
10. What did Ellegren’s analysis of microsatellite mutations show?
a) dinucleotide repeats tended to get longer, while tetranecleotide repeats tended to get shorter
b) dinucleotide repeats tended to get longer, while tetranecleotide repeats had no trend
c) dinucleotide repeats and tetranecleotide repeats tended to get longer
d) dinucleotide repeats tended to get shorter, while tetranecleotide repeats tended to get longer
e) dinucleotide repeats tended to get shorter, while tetranecleotide repeats had no trend
f) dinucleotide repeats and tetranecleotide repeats tended to get shorter
11. Humans have a DNA sequence that looks like the chimp gene for the CMAH enzyme, except
that humans have a 92 base pair deletion that makess it nonfunctional. This is an example of a
a) homoplasy b) vestigial trait
c) reversal
d) none of these
12. In the greenish warbler ring series
a) the northwestern and northeastern forms will
readily mate in their contact zone
b) the southwestern and southeastern forms will readily
mate in their contact zones c) a+b d) neither a nor b
13. The principle that geological processes taking place now operated similarly in the past is
a) ontological naturalism
b) homology c) homplasy d) catastrophism
e) uniformitarianism
14. Large fruit in domestic tomatoes is due to
a) high expression of a repressor protein
b) low expression of a repressor protein
c) high expression of auxins
d) low expression of auxins
15. Research by Jones and Reithel on snapdragons showed that
visits by bees
b) yellow flowers had higher seed set
a) yellow flowers had more
c) a+b
d) neither a nor b
16. The droughts of 1977 and 2003 affected medium ground finches by selecting for
a) increased beak depth in both cases
b) decreased beak depth in both cases
c) increased beak depth in 1977, but decreased in 2003
d) decreased beak depth in 1977, but
increased in 2003
17. How does the eel sperm flagellum differ from the more typical eukaryotic flagellum?
a) it lacks the central pair complex b) it lacks the A tubule
c) it lacks the B tubule
18. Why are short and long interspersed elements so useful in reconstructing phylogeny?
a) because homoplasy is very common
b) because their loss is associated with loss of a part
of the host genome c) a+b d) neither a nor b
19. How did Chameleons get from Africa to India a) they didn’t
b) they floated on rafts
c) they road chunks of Gondwana as it broke up
20. Most of the mutations isolated by Denver and colleagues from C. elegans nuclear DNA were
a) transitions b) transversions
c) indels
21. Which is the more common cause of gene duplication?
a) retrotransposition b) unequal cross-over
2
22. Est inversions in Drosophila are a) more common in higher latitudes in North America
b) more common in higher latitudes in south America
c) a+b
d) neither a nor b
23. Individuals of genotype CCR5-∆32/ CCR5-∆32 are
b) more common in northern Europe
c) a+b
a) more susceptible to HIV infection
d) neither a nor b
Short answers
1. (4 pts) At time 0, patients were switched from AZT to another anti-HIV treatment (DDI).
Draw the curves representing the sensitivity of the HIV virus to each of the two drugs after the
switch.
sensitivity
0
2
4
6
time (months)
8
2. (3 pts) After 8 years of chronic HIV infection, the HIV RNA stops diverging (as measured in
genetic distance) from the initial RNA of the infecting HIV. Why?
3. (3 pts) If you find a stickleback fish with four dermal plates, what is most likely its genetic
constitution (hint: remember to consider all of the genes influencing the phenotype)?
4. (4 pts) Research on the beak of the finch yielded the following graph. Give two plausible
interpretations of why this relationship could exist in finches.
Offspring
Beak
depth
parent beak depth
3
5. (6 pts) Please answer the questions based on the tree below.
A
B
C
D
E
F
G
a) Which species (may be more than one) is/are most closely related to E.
b) Which species (may be more than one) is/are most closely related to A
c) The area surrounded by the circle forms a ___________________ group.
6. (6 pts) When MutS+/MutS+ E. coli were competed against MutS-/MutS- E.coli in a novel
environment (with equal initial population size) there were some interesting dynamics.
a) Draw a graph that shows the results of this experiment
b) provide an explanation for this result.
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7. (3 pts) Please explain why the bones in the forelimb bones in bats and birds are homologous,
but the use of forelimbs for powered flight is homoplastic in these two groups.
8. (3 pts) Give a plausible explanation for why humans, chimps and orangatans share the 16
MYA processed pseudogene (AS7), while it is missing in gorillas.
9. (6 pts) a) Build a tree using the following DNA base sequence information
Species A
Species B
Species C
Species D
Species E
ATTGCAGCA
CTTGTAGGC
CATGTAGGC
ATTGCAGCC
CGAGTATTA
b) Identify one location on your tree where a reversal occurred (and what was that reversal)?
Name _______________________ (10 pts) There is lots of extra credit embedded in this exam.
Ace it!
(2 pts) The following statements pertain to questions 1-9. Fill in the letter that describes the
process that best explains each statement.
A) frequency dependent selection
B) directional selection
C) underdominance
D) heterozygote superiority (heterosis)
E) not an evolutionary process
_____1. explains the world-wide distribution of sickle-cell anemia
_____2. Explains fruit set in two color morphs of elderflower orchids
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_____3. the very flat insect on a branch probably resulted from this type of selection
_____4. Susceptibility to kuru
_____5. Fitness of individuals with a trait is variable
_____6. Mosquitoes evolve resistance to DDT
_____7. Foster’s research on selection on Drosophila with compound chromosomes
_____8. Decrease in lactose intolerance in Euro/American humans
_____9. Change in human cranial shape from American Colonial period to present
Multiple choice (2 pts each)
10. Genetic drift leads to evolutionary change more rapidly in which size populations?
a) small
b) medium
c) large
d) infinite
11. Genetic drift is more likely to lead to fixation of an allele more rapidly in which size
population?
a) small
b) medium
c) large
d) infinite
12. Collared lizards in the Ozark Mountains have
heterozygosity
b) fixation of different alleles in different small populations
nor b
a) a high degree of
c) a+b
d) neither a
13. Referring to question 12, what is an expected result of controlled burns conducted by the
Missouri Department of Conservation?
a) more gene flow
b) more genetic drift
c) larger populations
d) a+b
e) a+c
f) b+c
g) all of the above
14. Why does Kimura argue that natural selection’s effect on allele frequencies is relatively
small?
a) beneficial mutations are rare
b) deleterious mutations are selected out of the population
before they get established c) a+b d) neither a nor b
15. Gojobori’s study of the RNA sequence in influenza showed
a) support for the neutral
theory
b) a much higher rate of replacement mutations than synonymous mutations
c) a+b d)
neither a nor b
16. Andrew Young’s study of population size, allele richness and polymorphism showed a) a
higher allele richness in Eucalyptus than the other species b) polymorphism increased with
population size, but allele richness did not
c) good evidence for genetic drift being a
more potent force in large populations
d) a+b
e) a+c
f) b+c
g) all
of the above
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17. What is the inbreeding depression if the fitness of a selfed plant is 75% that of the fitness of
an outbred plant
a) .25 b) .5 c) .75 d) none of these
18. What type of mating system do prairie chicens have
polygyny
d) none of these
a) monogamy b) polyandry c) lek
19. Which is true of the prairie chicken population in Illinois?
a) hatching success has
increased since 1990 b) individuals were imported from other states to increase gene flow
c) a+b
d) neither a nor b
20. Experiments by Paul Weeks provide evidence that the interaction between oxpeckers and
cows is best described as
a) mutualism b) competition c) parasitism d) none of these
21. Which of the following treatments did Erick Greene use for his exeriments on spider mimicry
by tephritid fllies
a) Zonosemata with own wings cut and reglued
b) Zonosemata with
housefly wings
c) Housefly with Zonosemata wings d) a+b
e) a+c
f) b+c
g) all of the
above
22. Which groups show large testes in species with low levels of sperm competition?
primates
b) bats
c) a+b
d) neither a nor b
a)
23. Which is not part of Felsenstein’s comparative method for evaluating phylogenetically
independent contrasts?
a) figure out the phylogeny of the species b) plot all sister
species on a scatterplot
c) move the lines connecting the contrasts, so that the species with the lower x-value is at the
origin
d) erase the point at the origin
e) convert all continuous variables to nominal variables
24. Bat species with high relative testes size will usually have
b) moderate relative brain size
d) low relative brain size
a) high relative brain size
25. According to research by Schenske and Agren, female flower size in Begonia involuctra has
been determined by a) directional selection for smaller female flowers b) tradeoff between
flower color and floral retention
c) a+b
d) neither a nor b
26.Which of the following is an assumption of the Hardy-Weinberg equilibrium?
a) no natural selection
b) no gene flow
c) no random mating d) no genetic drift
e) all are assumptions of the Hardy-Weinberg equilibrium
27. Why have body feather lice switched hosts less frequently than wing feather lice?
a) because they are more firmly attached to the body feathers than the wing feather lice are to the
wing feathers b) they don’t hitchhike very often on parasitic flies c) a+b d) neither a nor b
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28. According to Gould and Lewontin, arguing that the spandrels of San Marcos were built as
spaces to house mosaics is analogous to
a) arguing that noses are adaptations for supporting
eyeglasses
b) arguing that all adaptations evolved to serve their current function
c) a+b d) neither a
nor b
29. (3 pts). DD and Dd individuals have 25% survival rates and dd individuals have a 20%
survival rate. They all produce the same number offspring on average. Calculate the fitnesses
and selections coefficients.
30. (9 pts) a). In a population of elk 10 males with the largest antlers fathered 200 fawns while
the 100 smaller antlered males fathered 220 fawns. What are the reproductive fitnesses and
selection coefficients of the 2 types of males?
b) Of the 10 large antlered elk that mated in the spring, five survived through the following
winter to mate again. Of the 100 smaller antlered males, 70 were still alive the following spring.
What are the survival fitnesses and selection coefficients of the 2 types of males?
c) What are the overall fitnesses of the large and small antlered males in question 30 if you
consider their abilities to survive and reproduce?
31. (4 pts) A population of reindeer is in Hardy-Weinberg equilibrium for a gene for nose color,
in which having a red nose is determined by a recessive allele. A population geneticist named
Sandy Claws finds 64 red-nosed reindeer in his flock of 100. What is the frequency of the
recessive allele.
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32. (6 pts) What did Gerald Pier and colleagues hypothesize regarding why cystic fibrosis is so
prevalent in the human population, despite having a negative influence on fitness of affected
individuals?
b) Describe two research findings that support their hypothesis?
33. (5 pts) The following population of individuals is not in hardy Weinberg Equilibrium.
numbers of
individuals
AA
Aa
aa
10
140
50
a) What is the allele frequency?
b) What will be the genotype frequencies the next generation if it returns to Hardy-Weinberg
equilibrium?
34 (6 pts). a) What are two alternatives discussed by Gould and Lewontin to the adaptationist
programme.
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b) Give an example of each alternative that you’ve learned about in this class.
34. (14 pts) Alarm calls are common in ground squirrels of several species. When a squirrel
squeals the equivalent of "heads up", all the squirrels are supposed to scurry into their little holes
and hide. If they do, they avoid getting eaten by predators. In a really silly population of 100
squirrels, only 19 respond to the "heads up" squeal by scurrying into a hole and hiding, while the
remaining 81 respond by "sticking their heads out the hole", and thus suffer a mortality (death)
rate of 70% before reaching reproductive age.
Assume that squirrels who stick their heads out of a hole (instead of hiding) are homozygous for
a recessive allele. Assume that our population initially was in Hardy-Weinberg equilibrium.
a) What are the allele frequencies?
b) What are the genotype frequencies
c) What is the selection coefficient operating against the "sticking their head out the hole"
phenotype?
d) Given your answer to C, if there are also 100 squirrels next generation, what number (you will
have to round off to the nearest squirrel) will stick their heads out of the hole in response to
"heads up"?
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e) What will be the allele frequency of the "sticking their head out of the hole" allele next
generation (no longer in HW equilibrium)?
36. (4 pts) If A population of 10 individuals has 20% heterozygosity, what is the expected %
heterozygosity in the next generation as a result of genetic drift?
Name (10 pts if printed) __________________________________ Biology 425
Exam
Final
1. Which of the following are predictions of the rate of living theory for the evolution of aging?
a) aging rate is negatively correlated with metabolic rate b) species can be selected to evolve
longer life-spans
c) a+b d) neither a nor b
2. Which group had the highest lifetime energy expenditure in Austad and Fisher’s study?
a) bats
b) carnivores
c) artiodactyls (deer) d) lagomorphs (rabbits)
3. Which influenza virus is most dangerous to humans
a) A
b) B
c) C
4. How did the flue pandemic of 1918 differ from the flu outbreaks in the previous years?
a) it inflicted high mortality on people in their 20s and 30s. b) it was an RNA virus c) a+b
d) neither a nor b
5. Which of the following is true about the distribution of breast cancer?
a) breast cancer incidence is higher in Eastern Europe than Western Europe
b) breast
cancer incidence is highest in areas with Mus musculus
c) a+b
d) neither a nor b
6. Strassmann’s results on Dogon women, and on women in other West African communities,
suggest that a) breast cancer is caused by high levels of childbirth
b) breast cancer is
caused by a virus
c) a+b d) neither a nor b
7. In what ways are the Africanized honeybees less desirable than their European counterparts?
a) more susceptible to disease
b) more likely to swarm
c) lower pollination
rates d) a+b e) a+c
f) b+c
g) all of the above
11
8. The evolutionary psychology principle that different neural circuits are specialized for solving
different adaptive problems is exemplified by a) our ability to learn to solve complex problems
b) our tendency to make simplifications of our experiences c) the brain functions as a
computer
d) instincts
9. Which species has the fewest chromosomes?
gorilla
a) humans
b) chimpanzees
c)
10. In which tissue is the FOXP2 gene product much more highly expressed in humans in
comparison to other primates?
a) brain
b) blood
c) liver
d) heart
11. Current evidence supports the hypothesis that chimps and bonobos shared a common
ancestor most recently with a) humans
b) gorillas
c) orangatans
d) gibbon
12. Comparisons of Neanderthal to modern humans indicate that a) there was no evidence of
culture in Neanderthals
b) Neanderthals had smaller cranial capacity
c)
neanderthals have identical hyoid bones d) a+b
e) a+c f) b+c g) all of the above
13. Blasting the mitochondrial D-loop hypervariable region 1 DNA of modern humans vs.
Neanderthals and comparing % similarity against comparisons with other species that hybridize
and produce non-viable offaspring indicates a) modern human and Neanderthal % similarity is
greater than the other pairs
b) modern human and Neanderthal % similarity is equivalent to the other pairs
c) modern
human and Neanderthal % similarity is less than the other pairs
14. Which species concepts defines a species on the basis of whether individuals are able to
successfully reproduce?
a) biological species concept
b) morphospecies concept
c) phylogenetic concept
15. Which speciation model has no physical barriers?
peripatric
d) sympatric
a) allopatric
b) parapatric c)
161. F2 hybrids of Pundamilia pundamilia and P. nyerei showed a) preference index of -.25
and low variance in mate choice
b) preference index of -.25 and high variance in mate
choice
c) preference index of 0 and low variance in mate choice d) preference index of 0 and high
variance in mate choice
e) preference index of +.25 and low variance in mate
choice f) preference index of +.25 and high variance in mate choice
17. Which continents have had avian flu outbreaks that affected humans? a) North America
b) Africa
c) Asia
d) a+b
e) a+c
f) b+c
g) all of the above
18. Which virus is more lethal in mice?
a) DK/12
b) DK/27
19. Which taxonomic group goes against the trend that diversification and speciation is
correlated with the number of Hox genes? a) mammals b) sea urchins c) fruit flies
molluscs
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d)
20. Which of the following is true? a) Closely related species will tend to have a greater
number of similar Hox genes than distantly related species b) Closely related species will tend
to have Hox genes that are expressed in similar locations of the body than more distantly related
species
c) a+b
d) neither a nor b
21. Which of the following are selected for by intersexual selection?
a) copulatory plugs
b) sperm removal function of damselfly penis
c) a+b
d) neither a
nor b
22. How do Hawaiian drosopholids support the dispersal mechanism of speciation?
a) flies on more recently formed islands are more similar genetically
b) because lava flows
within the islands created two distinct populations of flies
c) a+b
d) neither a
nor b
23. Analysis of snapping shrimp sister pairs on either side of the isthmus of Panama support
which speciation hypothesis? a) dispersal b) parapatric c) peripatric d) sympatric e)
vicariance
24. In female Gunnison’s prairie dogs
a) fertility rates were higher if the female had
multiple mates
b) surviving litter size was higher if the female had multiple mates
c) a+b
d) neither a
nor b
25. In the pipefish Sygnathus typhle, males prefer females with
many spots
c) a+b
d) neither a nor b
a) large skin folds
b)
26. Delph’s study showed that when animal pollinated plants have flowers that are sexually
dimorphic for investment in pollinator attraction, investment by males tends to be larger in
a) number of flowers per inflorescence
b) strength of floral odor
c) nectar
quantity
d) a+b
e) a+c
f) b+c
g) all of the above
27. In the Yanomamo a) 40% of the men commit homicide b) homicidal men have more
children than non-homicidal men
c) a+b d) neither a nor b
28. At the U.S. Military academy at West Point, taller men had, over the course of a lifetime
a) more wives b) younger second wives
c) more children
d) a+b
e) a+c
f) b+c
g) all of the above
h) none of the above
29. Pryke and Anderson’s study on red-collared widowbirds showed that a) long tails caused
health to decline
b) long tails caused reproductive success to decline
c) a+b
d) neither a nor b
30. What is r between full cousins? a) .5
b) .25 c) .125
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d) <.05
31. Quellar and colleagues showed that in slime molds
a) in the lab, wild-type cells have
high reproductive success
b) in the soil, wild-type cells are geenbeard altruists c) a+b
d) neither a nor b
32. Bell’s experiments on sticklebacks in Loberg Lake showed
a) a rapid increase in the frequency of the complete-plated morph
b) evidence for a two-year lifecycle
c) a+b
d) neither a nor b
33. Which graph that best shows the molecular clock assumption?
A
B
C
D
Number of
Base pair
substitutions
(Y axis for
all four graphs)
Amount of time elapsed since genetic divergence
a) A
b) B
c) C
d) D
34. Which of the following is true about bootstrapping a sequence of DNA that is 500 bases
long?
a) Each position (or site) is randomly chosen for each data set
b) it is unlikely that the actual
DNA sequence will be one of the data sets used in the bootstrap analysis
c) bootstrapping is used to determine which tree is most parsimonious
d) a+b
e) a+c
f) b+c
g) all are true
35. What did Ellegren’s analysis of microsatellite mutations show?
a) dinucleotide repeats tended to get longer, while tetranecleotide repeats had no trend
b) dinucleotide repeats tended to get longer, while tetranecleotide repeats tended to get shorter
c) dinucleotide repeats and tetranecleotide repeats tended to get longer
d) dinucleotide repeats tended to get shorter, while tetranecleotide repeats had no trend
e) dinucleotide repeats tended to get shorter, while tetranecleotide repeats tended to get longer
f) dinucleotide repeats and tetranecleotide repeats tended to get shorter
36. How did Chameleons get from Africa to India a) they didn’t
b) they floated on rafts
c) they road chunks of Gondwana as it broke up
37. Bat species with high relative testes size will usually have
b) moderate relative brain size
d) low relative brain size
a) high relative brain size
38. According to research by Schenske and Agren, female flower size in Begonia involuctra has
been determined by a) directional selection for smaller female flowers b) tradeoff between
flower color and floral retention
c) a+b
d) neither a nor b
39. Experiments by Paul Weeks provide evidence that the interaction between oxpeckers and
cows is best described as
a) mutualism b) competition
c) parasitism d) none of
these
14
40. Which of the following treatments did Erick Greene use for his exeriments on spider mimicry
by tephritid fllies
a) Zonosemata with own wings cut and reglued
b) Zonosemata with
housefly wings
c) Housefly with Zonosemata wings d) a+b
e) a+c
f) b+c
g) all of the
above
41. Andrew Young’s study of population size, allele richness and polymorphism showed a) a
higher allele richness in Eucalyptus than the other species b) polymorphism increased with
population size, but allele richness did not
c) good evidence for genetic drift being a
more potent force in large populations
d) a+b
e) a+c
f) b+c
g) all
of the above
42. Why does Kimura argue that natural selection’s effect on allele frequencies is relatively
small?
a) beneficial mutations are rare
b) deleterious mutations are selected out of the population
before they get established c) a+b
d) neither a nor b
Short answers
1 (6 pts). Briefly describe three studies (including the results) that provide evidence that fever is
an adaptive response by the body?
2. (4 pts) What did the 16S rRNA analysis reveal about the evolution of botulism?
3. (4 pts) What are four morphological or physiological adaptations favoring bipedalism in
modern humans?
15
4 (5 pts). Briefly describe 5 hypotheses for the adaptive significance of bipedalism in humans?
5 (4 pts). Here are two graphs. For each graph, draw in one curve for SCID newborns, and a
second curve for control.
Percentile
Percentile
Total lymphocytes/mm3
Total T-cells/mm3
6 (4 pts). Describe the sequence of events that occurred when researchers induced a DK/27 
DK/12 mutation in a virus after the mouse was inoculated with DK/27?
16
7 (7 pts). a) Discuss Andrade’s two hypotheses for why redback widow males threw themselves
into the jaws of their mates.
b) What evidence did she use to decide which hypothesis was likely to be correct?
8 (5 pts). Discuss the likely reproductive behavior of males and females based on the graph
below. Make sure you justify your argument.
females
Number of
Offspring
males
Number of Mates
17
9 (6 pts). a) What is Hamilton’s rule, and how does it relate to the evolution of altruism?
b) Discuss one study that demonstrates how Hamilton’s rule can help us understand the evolution
of altruistic behavior. Make sure your discussion includes a description of the question or
hypothesis addressed by the researchers, the experiments or observations, the results of the study,
and the conclusions.
10. (3 pts) Please explain why the bones in the forelimb bones in bats and birds are homologous,
but the use of forelimbs for powered flight is homoplastic in these two groups.
11. (4 pts) Research on the beak of the finch yielded the following graph. Give two plausible
interpretations of why this relationship could exist in finches.
Offspring
Beak
depth
parent beak depth
18
12. (9 pts) a). In a population of elk 20 males with the largest antlers fathered 100 fawns while
the 100 smaller antlered males fathered 150 fawns. What are the reproductive fitnesses and
selection coefficients of the 2 types of males?
b) Of the 20 large antlered elk that mated in the spring, five survived through the following
winter to mate again. Of the 100 smaller antlered males, 80 were still alive the following spring.
What are the survival fitnesses and selection coefficients of the 2 types of males?
c) What are the overall fitnesses of the large and small antlered males in question 30 if you
consider their abilities to survive and reproduce?
13. (14 pts) Alarm calls are common in ground squirrels of several species. When a squirrel
squeals the equivalent of "heads up", all the squirrels are supposed to scurry into their little holes
and hide. If they do, they avoid getting eaten by predators. In a really silly population of 100
squirrels, only 36 respond to the "heads up" squeal by scurrying into a hole and hiding, while the
remaining 64 respond by "sticking their heads out the hole", and thus suffer a mortality (death)
rate of 60% before reaching reproductive age.
Assume that squirrels who stick their heads out of a hole (instead of hiding) are homozygous for
a recessive allele. Assume that our population initially was in Hardy-Weinberg equilibrium.
19
a) What are the allele frequencies?
b) What are the genotype frequencies
c) What is the selection coefficient operating against the "sticking their head out the hole"
phenotype?
d) Given your answer to C, if there are also 100 squirrels next generation, what number (you will
have to round off to the nearest squirrel) will stick their heads out of the hole in response to
"heads up"?
e) What will be the allele frequency of the "sticking their head out of the hole" allele next
generation (no longer in HW equilibrium)?
20