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CAMPBELL
BIOLOGY
TENTH
EDITION
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
54
Community
Ecology
Clicker Questions by
Roberta Batorsky
© 2014 Pearson Education, Inc.
Two-species interactions are classified by the impact
each species has on the other. Thus, a competitive
interaction is one where the populations of each species
are hurt by the presence of the other species, usually
because each species uses the same resources. Niche
partitioning enables species to coexist by
a) avoiding direct competition.
b) encouraging mutualistic interactions.
c) enabling prey to hide from predators.
d) creating new resources.
e) allowing abiotic factors, such as climate or nutrient
availability, to influence the community.
© 2014 Pearson Education, Inc.
Two-species interactions are classified by the impact
each species has on the other. Thus, a competitive
interaction is one where the populations of each species
are hurt by the presence of the other species, usually
because each species uses the same resources. Niche
partitioning enables species to coexist by
a) avoiding direct competition.
b) encouraging mutualistic interactions.
c) enabling prey to hide from predators.
d) creating new resources.
e) allowing abiotic factors, such as climate or nutrient
availability, to influence the community.
© 2014 Pearson Education, Inc.
Which of the following best describes resource
partitioning?
a) Two species can coevolve to share identical niches.
b) Competitive exclusion results in the success of the
superior species.
c) A climax community is reached when no new niches
are available.
d) Slight variations in niche allow similar species
to coexist.
e) Differential resource utilization results in the decrease
in community species diversity.
© 2014 Pearson Education, Inc.
Which of the following best describes resource
partitioning?
a) Two species can coevolve to share identical niches.
b) Competitive exclusion results in the success of the
superior species.
c) A climax community is reached when no new niches
are available.
d) Slight variations in niche allow similar species
to coexist.
e) Differential resource utilization results in the decrease
in community species diversity.
© 2014 Pearson Education, Inc.
What is one difference between the fundamental niche
and the realized niche?
a) The realized niche is larger.
b) The fundamental niche is determined by competitors
c) The realized niche is determined by abiotic
resources.
d) Individuals will be found only in the realized
niche.
e) The difference is called the occupied niche.
© 2014 Pearson Education, Inc.
What is one difference between the fundamental niche
and the realized niche?
a) The realized niche is larger.
b) The fundamental niche is determined by competitors
c) The realized niche is determined by abiotic
resources.
d) Individuals will be found only in the realized
niche.
e) The difference is called the occupied niche.
© 2014 Pearson Education, Inc.
The common spiny mouse (Acomys cahirinus) and the
golden spiny mouse (A. russatus) can occupy
essentially the same ecological niche. They accomplish
this by
a) character displacement.
b) temporal niche partitioning.
c) eating different foods.
d) mating at different times of the year.
e) each occupying their functional niche.
© 2014 Pearson Education, Inc.
The common spiny mouse (Acomys cahirinus) and the
golden spiny mouse (A. russatus) can occupy
essentially the same ecological niche. They accomplish
this by
a) character displacement.
b) temporal niche partitioning.
c) eating different foods.
d) mating at different times of the year.
e) each occupying their functional niche.
© 2014 Pearson Education, Inc.
An obligate mutualism is an interaction in which at least one
species cannot survive without the presence of the other
species; a facultative mutualism is an interaction that benefits
both species but is not required by either species. One reason
facultative mutualism is more common is that
a) in an obligate mutualism, if the partner becomes extinct,
the obligate mutualist will also become extinct.
b) in a facultative mutualism, if the partner becomes extinct, the
obligate mutualist will also become extinct.
c) in an obligate mutualism, the obligate mutualist is obliged to
support its partner.
d) in a facultative mutualism, neither partner can depend on the
other partner.
e) facultative mutualisms require longer periods of time to evolve.
© 2014 Pearson Education, Inc.
An obligate mutualism is an interaction in which at least one
species cannot survive without the presence of the other
species; a facultative mutualism is an interaction that benefits
both species but is not required by either species. One reason
facultative mutualism is more common is that
a) in an obligate mutualism, if the partner becomes extinct,
the obligate mutualist will also become extinct.
b) in a facultative mutualism, if the partner becomes extinct, the
obligate mutualist will also become extinct.
c) in an obligate mutualism, the obligate mutualist is obliged to
support its partner.
d) in a facultative mutualism, neither partner can depend on the
other partner.
e) facultative mutualisms require longer periods of time to evolve.
© 2014 Pearson Education, Inc.
This graph shows the effect of soil pH on microbial diversity.
One conclusion you should draw from this figure is
a) the higher the soil pH,
the higher the microbial
diversity.
b) the lower the soil pH,
the higher the microbial
diversity.
c) microbes eat pH.
d) the scientists couldn’t find
any acidic or basic soils.
e) there appears to be an optimal pH value for
maximizing microbial diversity.
© 2014 Pearson Education, Inc.
This graph shows the effect of soil pH on microbial diversity.
One conclusion you should draw from this figure is
a) the higher the soil pH,
the higher the microbial
diversity.
b) the lower the soil pH,
the higher the microbial
diversity.
c) microbes eat pH.
d) the scientists couldn’t find
any acidic or basic soils.
e) there appears to be an optimal pH value for
maximizing microbial diversity.
© 2014 Pearson Education, Inc.
Look at the following figure, which shows a partial
Chesapeake Bay food web. If sea nettles disappeared,
a) there would be fewer
fish eggs.
b) there would be more
striped bass.
c) there would be fewer
zooplankton.
d) striped bass would
have less food to eat.
e) sea nettles would
reinvade from the ocean.
© 2014 Pearson Education, Inc.
Look at the following figure, which shows a partial
Chesapeake Bay food web. If sea nettles disappeared,
a) there would be fewer
fish eggs.
b) there would be more
striped bass.
c) there would be fewer
zooplankton.
d) striped bass would
have less food to eat.
e) sea nettles would
reinvade from the ocean.
© 2014 Pearson Education, Inc.
In rocky intertidal communities of western North America, Robert
Paine removed Pisaster, an uncommon starfish, and measured
species diversity. He found species diversity dropped dramatically
when Pisaster was not present. From this, we can conclude that
a) uncommon species are more vital
to the community than common species.
b) predators are more vital to the
community than prey.
c) Pisaster likely consumed
the dominant competitors.
d) Robert Paine’s experiment
was poorly designed.
e) removing one species
always hurts the community.
© 2014 Pearson Education, Inc.
In rocky intertidal communities of western North America, Robert
Paine removed Pisaster, an uncommon starfish, and measured
species diversity. He found species diversity dropped dramatically
when Pisaster was not present. From this, we can conclude that
a) uncommon species are more vital
to the community than common species.
b) predators are more vital to the
community than prey.
c) Pisaster likely consumed
the dominant competitors.
d) Robert Paine’s experiment
was poorly designed.
e) removing one species
always hurts the community.
© 2014 Pearson Education, Inc.
Disturbance is an important component of succession
because it
a) removes keystone species.
b) changes the biome from one kind to another.
c) introduces invasive species.
d) is associated with humans.
e) tends to promote earlier successional
stages.
© 2014 Pearson Education, Inc.
Disturbance is an important component of succession
because it
a) removes keystone species.
b) changes the biome from one kind to another.
c) introduces invasive species.
d) is associated with humans.
e) tends to promote earlier successional
stages.
© 2014 Pearson Education, Inc.
Which of the following explains mutualism?
a) − / −
b) + / −
c) + / +
© 2014 Pearson Education, Inc.
Which of the following explains mutualism?
a) − / −
b) + / −
c) + / +
© 2014 Pearson Education, Inc.
Scientific Skills Exercises
In the first part of an experiment, researchers collected
12 black snakes (Pseudechis porphyriacus) from areas
where cane toads had existed for 40–60 years and
another 12 from areas free of cane toads. They offered
the snakes either a freshly killed native frog
(Limnodynastes peronii, a species the snakes commonly
eat) or a freshly killed cane toad from which the toxin
gland had been removed (making the toad
nonpoisonous).
© 2014 Pearson Education, Inc.
The data are shown below, and a bar graph of the data is
shown on the next slide.
© 2014 Pearson Education, Inc.
© 2014 Pearson Education, Inc.
What do the data suggest about the effects of cane
toads on the predatory behavior of black snakes in
areas where the toads have been present for 40–60
years?
a) Black snakes will not prey on cane toads in areas
where cane toads have been present for 40–60
years.
b) Black snakes will prey on cane toads in areas where
cane toads have been present for 40–60 years, but
not when offered a native frog instead.
c) Black snakes in areas where cane toads have been
present for 40–60 years are just as likely to prey on
cane toads as on native frogs.
© 2014 Pearson Education, Inc.
What do the data suggest about the effects of cane
toads on the predatory behavior of black snakes in
areas where the toads have been present for 40–60
years?
a) Black snakes will not prey on cane toads in areas
where cane toads have been present for 40–60
years.
b) Black snakes will prey on cane toads in areas where
cane toads have been present for 40–60 years, but
not when offered a native frog instead.
c) Black snakes in areas where cane toads have been
present for 40–60 years are just as likely to prey on
cane toads as on native frogs.
© 2014 Pearson Education, Inc.
What do the data suggest about the predatory
behavior of black snakes in areas where cane toads
are not currently found
a) In those areas, black snakes will not prey on cane
toads.
b) In those areas, black snakes are equally likely to prey
on native frogs and cane toads.
c) In those areas, black snakes will prey on cane toads,
but they are more likely to prey on native frogs.
© 2014 Pearson Education, Inc.
What do the data suggest about the predatory
behavior of black snakes in areas where cane toads
are not currently found
a) In those areas, black snakes will not prey on cane
toads.
b) In those areas, black snakes are equally likely to prey
on native frogs and cane toads.
c) In those areas, black snakes will prey on cane
toads, but they are more likely to prey on native
frogs.
© 2014 Pearson Education, Inc.
Suppose an enzyme that deactivates the cane toad toxin
evolves in black snakes living in areas with cane toads. If
the researchers repeated this experiment, predict how the
results would change for areas where cane toads have
been present for 40–60 years.
a) A much higher percentage of black snakes in those areas
would eat the cane toads offered to them.
b) The results would not change significantly.
c) A much lower percentage of black snakes in those areas
would eat the cane toads offered to them.
d) A much higher percentage of black snakes in those areas
would eat the cane toads offered to them, and a lower
percentage would eat the native frogs offered to them.
© 2014 Pearson Education, Inc.
Suppose an enzyme that deactivates the cane toad toxin
evolves in black snakes living in areas with cane toads. If
the researchers repeated this experiment, predict how the
results would change for areas where cane toads have
been present for 40–60 years.
a) A much higher percentage of black snakes in those
areas would eat the cane toads offered to them.
b) The results would not change significantly.
c) A much lower percentage of black snakes in those areas
would eat the cane toads offered to them.
d) A much higher percentage of black snakes in those areas
would eat the cane toads offered to them, and a lower
percentage would eat the native frogs offered to them.
© 2014 Pearson Education, Inc.
Based on the scatter plot, what conclusion would you draw about
whether exposure to cane toads is having a selective effect on
black snakes in this study?
a) Exposure to cane toads does not appear to have a selective
effect on black snake populations.
b) Exposure to cane toads
appears to be selecting for
black snakes that are less
affected by the toxin.
c) Exposure to cane toads
appears to be selecting for
black snakes that are more
affected by the toxin.
d) Exposure to cane toads
appears to be selecting for
black snakes that are faster swimmers.
© 2014 Pearson Education, Inc.
Based on the scatter plot, what conclusion would you draw about
whether exposure to cane toads is having a selective effect on
black snakes in this study?
a) Exposure to cane toads does not appear to have a selective
effect on black snake populations.
b) Exposure to cane toads
appears to be selecting for
black snakes that are less
affected by the toxin.
c) Exposure to cane toads
appears to be selecting for
black snakes that are more
affected by the toxin.
d) Exposure to cane toads
appears to be selecting for
black snakes that are faster swimmers.
© 2014 Pearson Education, Inc.

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