Chapter 54 Community Ecology

Which of the following statements is consistent with the principle of competitive exclusion? A) Bird species generally do not compete for nesting sites. B) The density of one competing species will have a positive impact on the population growth of the other competing species.
C) Two species with the same fundamental niche will exclude other competing species. D) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species. E) Evolution tends to increase competition between related species.

D) Even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species.

According to the competitive exclusion principle, two species cannot continue to occupy the same A) habitat. B) niche.
C) territory. D) range. E) biome.

B) niche.

The sum total of an organism’s interaction with the biotic and abiotic resources of its environment is called its A) habitat. B) logistic growth.
C) biotic potential. D) carrying capacity. E) ecological niche.

E) ecological niche.

A species of fish is found to require a certain water temperature, a particular oxygen content of the water, a particular depth, a rocky substrate on the bottom, and a variety of nutrients in the form of microscopic plants and animals to thrive. These requirements describe its
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A) dimensional profile. B) ecological niche. C) prime habitat. D) resource partition. E) home base.

B) ecological niche.

Which of the following best describes resource partitioning? A) Competitive exclusion results in the success of the superior species. B) Slight variations in niche allow similar species to coexist. C) Two species can coevolve to share the same niche. D) Differential resource utilization results in the decrease in species diversity E) A climax community is reached when no new niches are available.

B) Slight variations in niche allow similar species to coexist.

As you study two closely related predatory insect species, the two-spot and the three-spot avenger beetles, you notice that each species seeks prey at dawn in areas without the other species. However, where their ranges overlap the two-spot avenger beetle hunts at night and the three-spot hunts in the morning. When you bring them into the laboratory, their offspring behave in the same manner. You have discovered an example of
A) mutualism. B) character displacement. C) Batesian mimicry. D) facultative commensalism. E) resource partitioning

B) character displacement.

Resource partitioning would be most likely to occur between A) sympatric populations of a predator and its prey. B) sympatric populations of species with similar ecological niches. C) sympatric populations of a flowering plant and its specialized insect pollinator. D) allopatric populations of the same animal species.
E) allopatric populations of species with similar ecological niches.

B) sympatric populations of species with similar ecological niches.

Which of the following is an example of cryptic coloration? 3
A) bands on a coral snake B) brown color of tree bark C) markings of a viceroy butterfly D) colors of an insect-pollinated flower E) a "walking stick" insect that resembles a twig

E) a "walking stick" insect that resembles a twig

Which of the following is an example of Müllerian mimicry? A) two species of unpalatable butterfly that have the same color pattern B) a day-flying hawkmoth that looks like a wasp C) a chameleon that changes its color to look like a dead leaf D) two species of rattlesnakes that both rattle their tails E) two species of moths with wing spots that look like owl’s eyes

A) two species of unpalatable butterfly that have the same color pattern

Which of the following is an example of Batesian mimicry? A) an insect that resembles a twig B) a butterfly that resembles a leaf C) a non-venomous snake that looks like a venomous snake
D) a fawn with fur coloring that camouflages it in the forest environment E) a snapping turtle that uses its tongue to mimic a worm, thus attracting fish

C) a non-venomous snake that looks like a venomous snake

Which of the following is an example of aposematic coloration? A) stripes of a skunk B) eye color in humans C) green color of a plant
D) colors of an insect-pollinated flower E) a katydid whose wings look like a dead leaf

A) stripes of a skunk

Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain nutrients and water from the vascular tissues of the trees. The trees derive no known benefits from the dwarf mistletoes. Which of the following best describes the interactions between dwarf mistletoes and trees?
A) mutualism
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B) parasitism C) commensalism D) facilitation E) competition

B) parasitism

Evidence shows that some grasses benefit from being grazed. Which of the following terms would best describe this plant-herbivore interaction? A) mutualism B) commensalism
C) parasitism D) competition E) predation

A) mutualism

Which of the following terms best describes the interaction between termites and the protozoans that feed in their gut? A) commensalism B) mutualism
C) competitive exclusion D) ectoparasitism E) endoparasitism

B) mutualism

Which of the following types of species interaction is correctly paired with its effects on the density of the two interacting populations? A) predation: as one increases, the other increases B) parasitism: both decrease
C) commensalism: as one increases the other stays the same D) mutualism: both decrease E) competition: both increase

C) commensalism: as one increases the other stays the same

White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-breasted nuthatch searches from the top of
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the trunk down. These hunting behaviors best illustrate which of the following ecological concepts? A) competitive exclusion B) resource partitioning
C) character displacement D) keystone species E) individualistic hypothesis

B) resource partitioning

Monarch butterflies are protected from birds and other predators but the cardiac glycosides they incorporate into their tissues are from eating milkweed when they were in their caterpillar stage of development. The wings of a different species of butterfly, the Viceroy, look nearly identical to the Monarch so predators that have learned not to eat the bad-tasting Monarch avoid Viceroys as well. This example best describes
A) aposmatic coloration. B) cryptic coloration. C) Batesian mimicry. D) Müllerian mimicry. E) mutualism.

C) Batesian mimicry.

All of the following have been used by plants to avoid being eaten except A) possessing spines and thorns on stems and leaves. B) synthesis of chemical toxins, such as strychnine, nicotine, and tannins. C) producing chemicals that are distasteful to herbivores, such as cinnamon, cloves, and peppermint.
D) producing tissues that have unappealing colors. E) synthesizing chemicals that can cause abnormal development in some insects that eat them.

D) producing tissues that have unappealing colors.

The species richness of a community refers to the A) complexity of the food web. B) number of different species. C) the bottom-heavy shape of the energy pyramid. D) relative numbers of individuals in each species. E) total number of all organisms.

B) number of different species.

With a few exceptions, most of the food chains studied by ecologists have a maximum of how many links? A) 2 B) 3
C) 5 D) 10 E) 15

C) 5

Which of the following members of a marine food chain occupies a similar tropic level to a grasshopper in a terrestrial food chain? A) phytoplankton B) zooplankton
C) lobster D) sea lion E) shark

B) zooplankton

Approximately how many kg of carnivore production can be supported by a field plot containing 2000 kg of plant material? A) 20,000 B) 2,000
C) 200 D) 20 E) 2

D) 20

The dominant species in a community is A) characterized by very large individuals with long lives. B) the best competitor in the community. C) the best predator in the community. D) the species that contributes the most biomass to the community. E) the most energetically efficient species in the community.

D) the species that contributes the most biomass to the community.

In a tide pool, 15 species of invertebrates were reduced to eight after one species was removed. The species removed was likely a(n) A) community facilitator. B) keystone species.
C) herbivore. D) resource partitioner. E) mutualistic organism.

B) keystone species.

Elephants are not the most common species in African grasslands. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Which of the following describes why elephants are the keystone species in this scenario?
A) Essentially all of the other species depend on the presence of the elephants to maintain the community. B) Grazing animals depend upon the elephants to convert forests to grassland. C) Elephants prevent drought in African grasslands.
D) Elephants are the biggest herbivore in this community. E) Elephants help other populations survive by keeping out many of the large African predators.

A) Essentially all of the other species depend on the presence of the elephants to maintain the community.

When lichens grow on bare rock, they may eventually accumulate enough organic material around them to supply the foothold for later rooted vegetation. These early pioneering lichens can be said to do what to the later arrivals? A) tolerate
B) inhibit C) facilitate D) exclude E) concentrate

C) facilitate

Which of the following is the most accepted hypothesis as to why invasive species take over communities into which they have been introduced? A) Invasive species are more aggressive than natives in competing for the limited resources of the environment.
B) Invasive species are not held in check by the predators and agents of disease that have always been in place for the natives. C) Humans always select which species will outcompete the nuisance native species. D) Invasive species have a higher reproductive potential than native species.
E) Invasive species come from geographically isolated regions, so when they are introduced to regions where there is more competition, they thrive.

B) Invasive species are not held in check by the predators and agents of disease that have always been in place for the natives.

According to the nonequilibrium model, A) communities will remain in a mature state if there are no human disturbances. B) community structure remains constant in the absence of interspecific competition. C) communities are assemblages of closely linked species that are irreparably changed by disturbance. D) interspecific interactions induce changes in community composition over time. E) communities are constantly changing after being influenced by disturbances.

E) communities are constantly changing after being influenced by disturbances.

You are most likely to observe primary succession in a terrestrial community when you visit a(n) A) tropical rain forest. B) abandoned field.
C) recently burned forest. D) recently created volcanic island. E) recently plowed field.

D) recently created volcanic island.

Which of the following describes the relationship between ants and acacia trees? A) parasitism B) mutualism C) inhibition
D) facilitation E) commensalism

B) mutualism

Which of the following describes a successional event in which one organism makes the environment more suitable for another organism? A) parasitism B) mutualism
C) inhibition D) facilitation E) commensalism

D) facilitation

A community’s actual evapotranspiration is a reflection of 10
A) solar radiation, temperature, and water availability. B) the number of plants and how much moisture they lose. C) the depth of the water table. D) energy availability. E) plant biomass and plant water content.

A) solar radiation, temperature, and water availability.

The feeding relationships among the species in a community determine the community’s A) secondary succession. B) ecological niche. C) species richness.
D) species-area curve. E) trophic structure.

E) trophic structure.

The principle of competitive exclusion states that A) two species cannot coexist in the same habitat. B) competition between two species always causes extinction or emigration of one species. C) competition in a population promotes survival of the best-adapted individuals. D) two species that have exactly the same niche cannot coexist in a community. E) two species will stop reproducing until one species leaves the habitat.

D) two species that have exactly the same niche cannot coexist in a community.

Based on the intermediate disturbance hypothesis, a community’s species diversity is increased by A) frequent massive disturbance. B) stable conditions with no disturbance.
C) moderate levels of disturbance. D) human intervention to eliminate disturbance. E) intensive disturbance by humans.

C) moderate levels of disturbance.

According to the equilibrium model of island biogeography, species richness would be greatest on an island that is A) large and close to a mainland. B) large and remote.
C) small and remote. D) small and close to a mainland. E) environmentally homogeneous.

A) large and close to a mainland.

Keystone predators can maintain species diversity in a community if they A) competitively exclude other predators. B) prey on the community’s dominant species. C) allow immigration of other predators.
D) reduce the number of disruptions in the community. E) prey only on the least abundant species in the community.

B) prey on the community’s dominant species.

Food chains are sometimes short because A) only a single species of herbivore feeds on each plant species. B) local extinction of a species causes extinction of the other species in its food chain. C) most of the energy in a trophic level is lost as it passes to the next higher level. D) predator species tend to be less diverse and less abundant than prey species. E) most producers are inedible.

C) most of the energy in a trophic level is lost as it passes to the next higher level.

Which of the following could qualify as a top-down control on a grassland community? A) limitation of plant biomass by rainfall amount B) influence of temperature on competition among plants C) influence of soil nutrients on the abundance of grasses versus wildflowers
D) effect of grazing intensity by bison on plant species diversity E) effect of humidity on plant growth rates

D) effect of grazing intensity by bison on plant species diversity

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is that A) tropical communities are younger. B) tropical regions generally have more available water and higher levels of solar radiation. C) higher temperatures cause more rapid speciation.
D) diversity increases as evapotranspiration decreases. E) tropical regions have very high rates of immigration and very low rates of extinction.

B) tropical regions generally have more available water and higher levels of solar radiation.