Chapter 17

Question 1

Initially devastating to Australian rabbits, myxoma virus became less lethal within a few years of
its introduction as a biological control agent. Why?
A) evolution of resistance on the part of rabbits
B) evolution of reduced virulence on the part of the virus
C) both of the above

Answer 1

C) both of the above

Question 2

Coevolution, by definition, cannot occur between a biological population and an abiotic factor.
A) True B) False

Answer 2

A) True

Question 3

Which of the following situations is most likely to meet the requirements of a strict definition of
coevolution?
A) the ability of hyenas to crack the bones of prey they have captured and killed
B) the ability of bears to climb forest trees
C) the ability of snowshoe hares to survive the harsh arctic winter
D) the ability of an insect herbivore to detoxify antiherbivore substances produced by its host
plant

Answer 3

D) the ability of an insect herbivore to detoxify antiherbivore substances produced by its host
plant

Question 4

Which of the following antipredator defenses is more likely to be found in an animal that is
palatable to its predators?
A) crypsis B) aposematism

Answer 4

A) crypsis

Question 5

Aposematic animals have conspicuous markings and bright colors, which serve as warnings to
would‐be predators. You find a brightlycolored butterfly that is unknown to you. Can you safely
conclude that this butterfly is distasteful to predators?
A) Yes, all conspicuously marked animals are distasteful to predators.
B) No, some conspicuously marked animals are palatable to predators.

Answer 5

B) No, some conspicuously marked animals are palatable to predators.

Question 6

Which of the following biologists has been honored by having his name associated with a type
of mimicry in which a palatable model mimics an unpalatable model?
A) Charles Darwin B) Fritz Müller C) Gregor Mendel D) Henry Bates

Answer 6

D) Henry Bates

Question 7

When one prey species mimics another unpalatable prey species (the model) to reduce its own
risk of predation, the mimic is always palatable to predators.
A) True B) False

Answer 7

B) False

Question 8

When one prey species mimics another unpalatable prey species (the model) to reduce its own
risk of predation, the mimic is always a close relative of the model.
A) True B) False

Answer 8

B) False

Question 9

The evolutionary biologist Charles Mode proposed a model of host‐pathogen evolution that
predicted cyclic change in frequencies of host resistance and pathogen virulence through time.
Which of the following was a key element in Mode’s model?
A) control of virulence and resistance by single dominant genes
B) costs associated with virulence and resistance, by themselves, to host and pathogen,
respectively
C) fitness of host or pathogen contingent on the genotype of the other
D) all of the above

Answer 9

D) all of the above

Question 10

What kind of approach did Ehrlich and Raven take in their research on coevolution, published in
1964?
A) recording repeating patterns in nature and inferring from these coevolutionary
relationships
B) developing elegant mathematical models and testing their predictive ability
C) conducting carefully designed, controlled experiments on parasitoids and their hosts
D) none of the above

Answer 10

A) recording repeating patterns in nature and inferring from these coevolutionary
relationships

Question 11

David Pimentel established an experimental population of houseflies from stock that had a long
history of prior experience with a parasitoid wasp. He also introduced parasitoid wasps into this
population and observed the change in numbers of the two species through time. The flies in
this experiment:
A) immediately went extinct.
B) exhibited dramatic oscillations.
C) exhibited a stable and relatively high constant population level.
D) none of the above

Answer 11

C) exhibited a stable and relatively high constant population level.

Question 12

In Pimentel’s experiments with houseflies and their parasitoids (see previous question), he
created two treatments. In one treatment, the host population (houseflies) was not permitted
to evolve responses to the parasitoid, whereas evolution of host responses was permitted in
the other treatment. What happened to the parasitoid population in the treatment in which
host evolution was permitted?
A) The parasitoid population maintained constant fecundity and life span.
B) The parasitoid population exhibited reduced fecundity and shorter life span.
C) The parasitoid population exhibited an increase in both fecundity and life span.
D) none of the above

Answer 12

B) The parasitoid population exhibited reduced fecundity and shorter life span.

Question 13

Which of the following statements correctly characterizes the status of pathogen resistance in
cultivated crops, such as wheat?
A) The system is in constant flux, as new virulent strains of pathogens appear and crop
breeders select resistant strains of the crop.
B) The system is stable because no new strains of the pathogen emerge.
C) The system is stable because strains of the crop have been produced that are resistant to all
strains of pathogens.

Answer 13

A) The system is in constant flux, as new virulent strains of pathogens appear and crop
breeders select resistant strains of the crop.

Question 14

The rust‐wheat system has an essential element of coevolution envisioned by Charles Mode.
What is it?
A) Virulence of the rust and resistance in wheat are not heritable traits.
B) There is an interaction between the fitnesses of the genotypes of the host and the
genotypes of the pathogen.
C) Only the host is capable of an evolutionary response.
D) Only the pathogen is capable of an evolutionary response.

Answer 14

B) There is an interaction between the fitnesses of the genotypes of the host and the
genotypes of the pathogen.

Question 15

As illustrated in the simple model of Figure 17.12, the balancing influences of consumer and
resource adaptation can achieve an evolutionary equilibrium. What is happening at this point?
A) Both consumer and resource cease evolving.
B) Both consumer and resource continue to evolve to maintain this equilibrium.
C) The consumer ceases to evolve but the resource continues to evolve in response to
continued consumption.
D) The resource ceases to evolve but the consumer continues to evolve in response to scarcity
of the resource.

Answer 15

B) Both consumer and resource continue to evolve to maintain this equilibrium.

Question 16

Which hypothesis, introduced in Chapter 8 as part of the discussion of sexual reproduction,
applies well to the evolutionary equilibrium illustrated in Figure 17.12?
A) the “Red Queen” hypothesis C) the “Pimentel” hypothesis
B) the “Lotka‐Volterra” hypothesis D) the “Bates‐Müller” hypothesis

Answer 16

A) the “Red Queen” hypothesis

Question 17

When consumer and resource populations in evolutionary equilibrium (see Figure 17.12)
experience a sudden environmental change that leads to a much higher rate of exploitation,
which population is likely to experience greater selective pressure and thus exhibit the greater
rate of evolutionary change?
A) the consumer B) the resource C) neither the resource nor the consumer

Answer 17

B) the resource

Question 18

In studies conducted by David Pimentel and colleagues, houseflies and blowflies were grown
together in an experimental cage that permitted long‐term coexistence of the two species.
During one 70‐week study, blowflies remained at low levels throughout most of the
experiment, but, at about 50 weeks, they showed a dramatic population increase, at the
expense of the houseflies. The evolution of superior competitive ability by a rare competitor is
an example of what kind of selection?
A) frequency‐dependent
B) balancing
C) neutral
D) dominant/recessive

Answer 18

A) frequency‐dependent

Question 19

Two species of grain beetles (identified only as 1 and 2) are collected in the field and
maintained under laboratory conditions for 1 year, encompassing many generations. Some of
the grain beetles are maintained in pure culture (P1 and P2) and others in mixed culture (M1
and M2), all under conditions of limiting food resources. At the end of the year, grain beetles of
species 1 from the mixed culture are tested for their competitive ability against the other
species from pure culture (M1 ‐ P2). A similar test is conducted, pitting grain beetles of species
1 from pure culture against the other species from pure culture (P1 ‐ P2). In which case would
you expect species 1 to show greater competitive ability with species 2?
A) M1 ‐ P2
B) P1 ‐ P2
C) M1 and P1 should exhibit identical competitive abilities against P2.

Answer 19

A) M1 ‐ P2

Question 20

Character displacement:
A) refers to Aunt Edna’s forgetting where she put her sense of values.
B) refers to the evolution of different species in isolation.
C) can be identified by comparing populations in allopatry and sympatry.
D) is restricted to animal populations because it refers to feeding adaptations.

Answer 20

C) can be identified by comparing populations in allopatry and sympatry.

Question 21

Related species that live together typically differ in the way they use resources. This is evidence
that these differences have evolved as a result of competitive interactions.
A) True B) False

Answer 21

B) False

Question 22

Species 1 occurs in areas A and B, and its close relative, species 2, occurs in areas B and C.
Areas A, B, and C all have similar environmental conditions and habitats. Which of the following
might we reasonably expect?
A) The sympatric populations of species 1 and 2 in area B will differ less from each other than
the allopatric populations of these two species in areas A and C.
B) The sympatric populations of species 1 and 2 in area B will differ more from each other than
the allopatric populations of these two species in areas A and C.
C) The sympatric populations of species 1 and 2 in area B will differ about as much from each
other as the allopatric populations of these two species in areas A and C.
D) none of the above

Answer 22

B) The sympatric populations of species 1 and 2 in area B will differ more from each other than
the allopatric populations of these two species in areas A and C.

Question 23

The ground finch genus Geospiza consists of several species distributed haphazardly across the
Galapagos Islands. When two or more Geospiza species occur on the same island, the beak size
ranges for these species:
A) are identical. B) tend to overlap considerably. C) exhibit no overlap.

Answer 23

. C) exhibit no overlap.

Question 24

Geospiza fuliginosa occurs in isolation on Daphne Island and G. fortis occurs in isolation on Los
Hermanos Island in the Galapagos. Their bill size ranges overlap considerably (refer to Figure
17.17). In 1925, an overzealous tourist captured several individuals from each population and
successfully established these on nearby Cocos Island, where ground finches did not occur. In a
recent survey, you measured bill sizes from a large sample of both species on Cocos Island.
What did you find?
A) The two species retained bill size ranges identical to the parental populations.
B) The two species had diverged somewhat in their bill size ranges.

Answer 24

B) The two species had diverged somewhat in their bill size ranges.

Question 25

A well‐studied mutualism involves ants, aphids, and leafhoppers. The ants protect the aphids
and leafhoppers from predators and are rewarded with the nutritious honeydew secreted by
these insects. What can we conclude from this mutualism?
A) A mutualism with this degree of specificity appears to represent coevolution.
B) A mutualism with this degree of specificity does not appear to represent coevolution.
C) We have insufficient evidence to conclude either A or B.

Answer 25

C) We have insufficient evidence to conclude either A or B.

Question 26

The tropical leguminous tree, Dioclea macrocarpa, produces L‐canavanine, an amino acid that is
toxic to most insects. D. macrocarpa lacks close relatives that produce this amino acid. A
bruchid beetle, Caryedes brasiliensis, has enzymes that enable it to feed on D. macrocarpa. C.
brasiliensis lacks close relatives that produce these enzymes.What can we conclude from this
mutualism?
A) A mutualism with this degree of specificity appears to represent coevolution.
B) A mutualism with this degree of specificity does not appear to represent coevolution.
C) We have insufficient evidence to conclude either A or B.

Answer 26

A) A mutualism with this degree of specificity appears to represent coevolution.

Question 27

Why do plants having strong chemical defenses against herbivores, such as angular
furanocoumarins (AFCs), sometimes suffer high levels of insect herbivory?
A) Insect herbivores destroy the plants before the toxins produce an effect.
B) These chemical defenses are only produced seasonally.
C) Some insect herbivores can tolerate these defenses and can feed freely on the plants.
D) These chemical defenses are easily tolerated by many generalist insect herbivores.
E) Structural defenses are not present.

Answer 27

C) Some insect herbivores can tolerate these defenses and can feed freely on the plants

Question 28

In May Berenbaum’s studies of the coevolution of plants in the parsley family (Umbelliferae)
and their insect herbivores, groups of plant species that evolved more recently were
characterized as:
A) more diverse and having less toxic chemical defenses against herbivores.
B) more diverse and having more toxic chemical defenses against herbivores.
C) less diverse and having less toxic chemical defenses against herbivores.
D) less diverse and having more toxic chemical defenses against herbivores.

Answer 28

D) less diverse and having more toxic chemical defenses against herbivores.

Question 29

Insects feeding on umbelliferous plants containing the highly toxic angular fumarocoumarins
(AFCs):
A) had close relatives feeding on other umbelliferous plants containing similar but less toxic
chemical defenses.
B) were unrelated to insects feeding on other umbelliferous plants containing similar but less
toxic chemical defenses.
C) none of the above

Answer 29

A) had close relatives feeding on other umbelliferous plants containing similar but less toxic
chemical defenses

Question 30

The branch of evolutionary biology that uses similarities and differences among species to
determine their evolutionary relationships is known as:
A) biochemical ecology C) phylogenetic determinism
B) biogeochemistry D) phylogenetic reconstruction

Answer 30

D) phylogenetic reconstruction

Question 31

In the yucca‐moth mutualism, the moth, Tegeticula, is the sole pollinator of the yucca, and the
yucca is the sole food source for the moth. Because of the tight and obligate relationship
between these two species, we would refer to this mutualism as a __________.
A) population B) community C) ecosystem D) ecotone E) symbiosis

Answer 31

E) symbiosis

Question 32

What adaptations on the part of yucca moths support their tight and obligate mutualistic
association with yuccas?
A) Individuals visit flowers of only a single species of yucca.
B) Mating occurs within the flowers.
C) Females lay their eggs within the ovary of the yucca flower.
D) Females have specially modified mouthparts that enable them to gather and transport
pollen.
E) all of the above

Answer 32

E) all of the above

Question 33

In the yucca‐moth mutualism, female Tegeticula moths exercise restraint, laying so few eggs in
Chapter 17: Evolution of Species Interactions
9
a yucca ovary that the resulting larvae will consume no more than about 30% of the seeds in a
developing fruit. Imagine that a “cheater” moth genotype arose, one that laid sufficient eggs to
consume all the seeds in a yucca fruit. Why would the fitness of this “cheater” genotype, which
could potentially produce more offspring per visit to a yucca flower, be lower than that of the
typical genotype?
A) because yucca moths are subject to group selection—groups exercising reproductive
restraint have greater fitness than groups not exercising restraint
B) because yuccas abort developing fruits that contain sufficient larvae to consume the
majority of seeds
C) because yuccas might eventually go extinct if the “cheater” genotype spread widely
D) none of the above

Answer 33

B) because yuccas abort developing fruits that contain sufficient larvae to consume the
majority of seeds

Question 34

Although the yucca‐moth mutualism appears to be highly coevolved, what appear to be
coevolved traits may have been preadaptations that were critical to the establishment of the
obligate mutualism in the first place.
A) True B) False

Answer 34

A) True

Question 35

Evolutionary biologists have coined the term __________ for situations in which populations
simultaneously respond to an array of complex interactions with many other species.
A) multiple mutualism C) diffuse coevolution
B) evolutionary steady‐state D) biosynthetic pathway

Answer 35

C) diffuse coevolution

Question 36

Interactions among species are major sources of selection and evolutionary response.
A) True B) False

Answer 36

A) True

Question 37

Rapid evolution of __________ was observed in populations of Australian rabbits subjected to a
virulent strain of myxoma virus.

Answer 37

resistance

Question 38

Reciprocal evolution between two interacting populations is referred to by evolutionary
biologists as __________.

Answer 38

coevolution

Question 39

In response to similar physical stresses in the environment, many kinds of organisms evolve
similar adaptations. Thus we find __________ in broadleaved evergreen trees that dominate
tropical rain forest ecosystems worldwide.

Answer 39

convergence

Question 40

When animals containing noxious chemicals advertise the fact with conspicuous color patterns,
we refer to this situation as __________.

Answer 40

warning coloration or aposematism

Question 41

When several unpalatable species adopt a single pattern of warning coloration, we refer to this
as __________ mimicry.

Answer 41

Müllerian

Question 42

Cornell ecologist David Pimentel and colleagues demonstrated evolutionary responses in
houseflies experiencing selection from a __________ wasp.

Answer 42

parasitoid

Question 43

When two species coexist within the same geographic area, their distributions are said to be
__________.

Answer 43

sympatric

Question 44

When two species have geographic distributions that do not overlap, they are said to be
__________.

Answer 44

allopatric

Question 45

If two related species exhibit differences related to resource acquisition when they co‐occur but
fail to show such differences when they occur separately, the differences noted when they cooccur
may have arisen through __________.

Answer 45

character displacement

Question 46

Toxic molecules synthesized by plants (such as angular furanocoumarins (AFCs) in Umbelliferae)
that deter herbivory are referred to as __________ compounds.

Answer 46

defensive