Chapter 18

Question 1

Which of the following concepts of community organization suggests that a community is much
more than the sum of its individual parts?
A) holistic concept B) individualistic concept C) neither of the above

Answer 1

A) holistic concept

Question 2

Which of the following concepts of community organization suggests that a community is
merely a fortuitous association of species whose adaptations and requirements enable them to
live together under the physical and biological conditions of a particular place?
A) holistic concept B) individualistic concept C) neither of the above

Answer 2

B) individualistic concept

Question 3

Identify the following statement with one of the following concepts of community organization:
“Each population within a community responds to evolutionary pressures with adaptations that
maximize the reproductive success of its individual members, regardless of any benefits to the
community as a whole.”
A) holistic concept B) individualistic concept C) neither of the above

Answer 3

B) individualistic concept

Question 4

Many European ecologists use a complex taxonomy of communities, based on a rigidly defined
method of sampling plant species composition, which places each community in a hierarchy of
types organized by their similarity. After whom is this system named?
A) R. H. Whittaker B) H. A. Gleason C) F. E. Clements D) J. Braun‐Blanquet

Answer 4

D) J. Braun‐Blanquet

Question 5

As discussed in the previous question, much effort has been devoted to classification of natural
communities, and this effort continues today. Which American ecologist would have found the
“pigeonholing” of natural communities into discrete classes most satisfying from a philosophical
perspective?
A) R. H. Whittaker B) H. A. Gleason C) F. E. Clements D) J. Braun‐Blanquet

Answer 5

C) F. E. Clements

Question 6

Which of the following correctly pairs related concepts?
A) holistic concept, open community
Chapter 18: Community Structure
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B) holistic concept, closed community
C) individualistic concept, open community
D) individualistic concept, closed community
E) both A and D
F) both B and C

Answer 6

F) both B and C

Question 7

Which of the following factors exhibits one of the most striking changes as one crosses the
ecotone between communities on serpentine and nonserpentine soils in southwestern
Oregon?
A) soil depth B) soil temperature C) soil chromium D) soil moisture

Answer 7

C) soil chromium

Question 8

Examine Figure 18.5. Which of the following species would you characterize as seemingly
Chapter 18: Community Structure
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unresponsive to changes in soil conditions across the ecotone between serpentine and
nonserpentine soils in southwestern Oregon?
A) black oak B) hawkweed C) ragwort D) fireweed

Answer 8

B) hawkweed

Question 9

Examine Figure 18.5. Which of the following species would you characterize as restricted to
nonserpentine soils in southwestern Oregon?
A) black oak B) hawkweed C) ragwort D) fireweed

Answer 9

A) black oak

Question 10

Examine Figure 18.5. Which of the following species would you characterize as restricted to
serpentine soils in southwestern Oregon?
A) black oak B) hawkweed C) ragwort D) fireweed

Answer 10

D) fireweed

Question 11

Examine Figure 18.5. Which of the following species would you characterize as restricted to the
ecotone between serpentine and nonserpentine soils in southwestern Oregon?
A) black oak B) hawkweed C) ragwort D) fireweed

Answer 11

C) ragwort

Question 12

Which of the following factors may be directly responsible for maintaining a sharp edge
between prairies and forests in the midwestern United States?
A) summer drought B) low winter temperatures C) tornadoes D) fire

Answer 12

D) fire

Question 13

The broadleaved deciduous forests of eastern North America contain many species of trees.
Which of the following statements best describes the geographic distributions of these species?
A) Groups of species found in any part of this region have very similar distributions.
B) Each species occupies a small geographic area from which all other species are excluded.
C) Each species has a different geographic range, but these ranges overlap to some extent.
D) none of the above

Answer 13

C) Each species has a different geographic range, but these ranges overlap to some extent.

Question 14

The tendency of certain forest species to occur in certain habitats (ridge tops or moist river
bottoms, for example) is convincing evidence for the closed community concept.
A) True B) False

Answer 14

B) False

Question 15

An animal ecologist interested in gradient analysis would:
A) measure the abundance of animal species and physical conditions at a number of locations
and then plot the abundance of each species as a function of one or more physical
conditions.
B) perform controlled crosses among all animal species within a community to determine the
extent to which the species are reproductively isolated.
C) compare the relative concentrations of all essential elements found in tissue samples taken
from all animal species within a community.
D) characterize the trophic structure of the community by determining “who eats whom.”

Answer 15

A) measure the abundance of animal species and physical conditions at a number of locations
and then plot the abundance of each species as a function of one or more physical
conditions.

Question 16

Robert H. Whittaker, in a study of plant distributions in Great Smoky Mountains National Park,
provided considerable support for:
A) the concept of open communities.
B) the concept of closed communities.
C) a novel concept that transcended the concepts of both closed and open communities.

Answer 16

A) the concept of open communities.

Question 17

Under which conditions in Great Smoky Mountains National Park would you seek communities
containing red oak, white oak, and beech? Refer to Figure 18.8.
A) low elevation, moist C) high elevation, moist
B) low elevation, dry D) high elevation, dry

Answer 17

D) high elevation, dry

Question 18

Biologists have catalogued all the species on earth, except for a few rare species in remote
tropical areas.
A) True B) False

Answer 18

B) False

Question 19

You are walking through a forest, and you soon discover that every other individual tree
belongs to a different species. Based on this fact alone, in which of the following countries are
you likely to be walking?
A) Ecuador B) United States C) Canada D) Sweden E) Poland

Answer 19

A) Ecuador

Question 20

You have been maintaining a list of the bird species that frequent your property. At the end of
the year you have tallied eight seed eaters, one nectar sipper, three woodpeckers, six
insectivores, two frugivores, four predators, and one carrion feeder. Which term best describes
each of the categories you have used in your tally?
A) community B) guild C) population D) habitat

Answer 20

B) guild

Question 21

Which of the following food web properties is independent of the species richness of the
community?
A) number of feeding links per species
B) number of trophic levels
C) number of guilds within trophic levels
D) overall food web complexity

Answer 21

A) number of feeding links per species

Question 22

Robert Paine conducted studies of rocky intertidal communities on the coast of Washington
and in the Gulf of California. Paine showed that removal of __________ consumers could result
in reduction of the number of their resource species.
A) predator B) herbivore C) both predator and herbivore

Answer 22

C) both predator and herbivore

Question 23

In the construction of food webs, much information can be obtained through simple
observation of feeding relationships within communities. Which of the following types of food
web could you construct from such observations, without further measurement or
experimentation?
A) connectedness web B) energy flow web C) functional web

Answer 23

A) connectedness web

Question 24

Constructing which of the following types of food web would require an experimental
approach?
A) connectedness web B) energy flow web C) functional web

Answer 24

C) functional web

Question 25

In a microcosm experiment, Chris Steiner and colleagues showed that resilience was positively
related to the number of species present, but only in __________‐productivity microcosms.
A) low B) high

Answer 25

A) low

Question 26

When Hairston, Smith, and Slobodkin suggested that the earth is green because carnivores
depress the populations of herbivores that would otherwise consume most vegetation, they
were focusing on __________ control of community structure.
A) top‐down B) bottom‐up

Answer 26

A) top‐down

Question 27

Hairston, Smith, and Slobodkin suggested that the earth is green because carnivores depress
the populations of herbivores that would otherwise consume most vegetation. Is this the only
possible explanation for the “earth is green” phenomenon?
A) Yes, there is no other plausible explanation.
B) No, perhaps the earth is green because most plants resist consumption through various
deterrents to herbivory.

Answer 27

B) No, perhaps the earth is green because most plants resist consumption through various
deterrents to herbivory.

Question 28

In a study conducted by Matthew Liebold and colleagues, the abundance of zooplankton was
positively correlated with the abundance of phytoplankton across a large number of natural
lakes, indicating __________ control by plant production of the abundance of organisms
feeding at higher trophic levels in aquatic systems.
A) top‐down B) bottom‐up

Answer 28

B) bottom‐up

Question 29

In the study referred to in the previous question, Matthew Leibold and colleagues added
predatory fish to experimental lakes. When fish were added, the abundance of zooplankton
decreased, and the abundance of phytoplankton increased, indicating __________ control by
predators of the abundance of organisms feeding at lower trophic levels in aquatic systems.
A) top‐down B) bottom‐up

Answer 29

A) top‐down

Question 30

In a study of ponds and nearby terrestrial ecosystems, Tiffany Knight and colleagues showed
that the presence of fish in ponds had indirect, positive effects on the seed set of terrestrial
plants. In particular, fish exerted this influence through their direct, negative effects on which
organisms?
A) larval dragonflies
B) adult dragonflies
C) insect pollinators of plants
D) plants

Answer 30

A) larval dragonflies

Question 31

Boundaries between communities in which there is rapid replacement of species belonging to
one community by those belonging to another are called __________.

Answer 31

ecotones

Question 32

Proponents of the __________ concept cite the continuous replacement of plants and animals,
one by another, along environmental gradients, as evidence supporting this concept.

Answer 32

individualistic

Question 33

Herbivores, large and small, are all referred to as __________ consumers.

Answer 33

primary

Question 34

Energy and nutrients follow many different, interconnected paths through the ecosystem,
collectively referred to as a __________.

Answer 34

food web

Question 35

__________ means feeding on more than one trophic level.

Answer 35

omnivory

Question 36

A consumer that promotes diversity by manipulating competitive relationships at a lower
trophic level is called a __________ consumer.

Answer 36

keystone

Question 37

A(n) __________ web emphasizes flux of energy as a means of defining interconnections
among species.

Answer 37

energy flow

Question 38

__________ is a measure of the ability of a system to resist change in the face of outside
influences.

Answer 38

constancy

Question 39

Ecologists tend to refer to the indirect effects of consumer‐resource interactions as they extend
through additional trophic levels of the community as a __________.

Answer 39

trophic cascade

Question 40

Ecosystems with high levels of primary productivity tend also to have greater productivity of
higher trophic levels, a compelling piece of evidence supporting the existence of __________
effects in ecosystems.

Answer 40

bottom-up