Deck 57: Community Ecology

Question 1

Which of the following statements about communities is false?

A) They can vary tremendously in size and scope.
B) An important factor in determining their species richness is the amount of energy available.
C) Energy enters communities through primary consumers.
D) An ecological community comprises a group of species that coexist and interact within a defined area.
E) All of the above are true; none is false.

Answer 1

C

Question 2

Which of the following statements about cheese skippers is true?

A) Their presence can be used to estimate the time of death of a body.
B) They are among the first species to arrive when a dead body starts decomposing.
C) They prefer hair and nails to flesh.
D) Both a and b
E) Both a and c

Answer 2

Their presence can be used to estimate the time of death of a body.

Question 3

Net primary production is

A) the total amount of photosynthesis in a community.
B) the total amount of primary producer biomass available for consumption by heterotrophs.
C) the total amount of biomass produced by all autotrophs and heterotrophs in a community.
D) the total amount of biomass consumed by heterotrophs.
E) gross primary productivity minus secondaryproductivity.

Answer 3

B

Question 4

Organisms that receive their energy from several trophic levels are said to be

A) detritivores.
B) herbivores.
C) primary consumers.
D) secondary consumers.
E) omnivores.

Question 5

A community ecologist would most likely be concerned with

A) energy flow through an ecosystem.
B) population growth of a single species.
C) interactions among individuals of the same species living together in a small area.
D) interactions among individuals of different species living together in a small area.
E) the cycling of matter through biotic and abiotic components of an area.

Question 6

Ecological succession is

A) the change in species over time.
B) the change in community composition after a disturbance.
C) the change in a forest as the trees grow larger.
D) the process by which a species becomes abundant.
E) the buildup of soil nutrients.

Question 7

Species diversity

A) increases with latitude from the equator to the temperate zone.
B) decreases with latitude from the equator to the temperate zone.
C) shows no consistent pattern from the equator to the temperate zone.
D) increases with latitude from the equator to the temperate zone for terrestrial organisms and decreases with latitude from the equator to the temperate zone for aquatic organisms.
E) increases with latitude from the equator to the temperate zone for animals and decreases with latitude from the equator to the temperate zone for plants.

Question 8

Early stages of succession are characterized by

A) species that are good dispersers.
B) species with high intrinsic rates of reproduction.
C) simple food webs.
D) nutrients that are available primarily in abiotic sources.
E) All of the above

Question 9

In a food web with energy flowing up, a(n) _______ is one trophic level above a primary consumer.

A) primary producer
B) decomposer
C) herbivore
D) autotroph
E) secondary consumer

Question 10

Keystone species

A) influence the communities in which they live more than expected on the basis of their abundance.
B) may influence the species richness of communities.
C) may influence the number of trophic levels in communities.
D) are not necessarily predators.
E) All of the above

Question 11

Primary succession begins

A) soon after a disturbance ends.
B) at varying times after a disturbance ends.
C) at sites where some organisms have survived a disturbance.
D) at sites where no organisms have survived a disturbance.
E) at sites where only primary producers have survived a disturbance.

Question 12

Organisms that are _______ acquire their energy from eating primary consumers.

A) primary producers
B) secondary consumers
C) herbivores
D) autotrophs
E) None of the above

Question 13

The theory of island biogeography

A) predicts that the equilibrium number of species on an island is a balance between the rate of immigration of new species and the rate of extinction of resident species.
B) predicts that the rate of immigration of new species will decline with island distance from the mainland species pool.
C) predicts that the rate of extinction of resident species will decrease as island size increases.
D) applies to isolated habitat patches as well as to oceanic islands
E) All of the above

Question 14

By definition, autotrophs are

A) primary consumers.
B) primary producers.
C) secondary consumers.
D) secondary producers.
E) decomposers.

Question 15

Pyramid diagrams of energy and biomass distribution for forests and grasslands differ because

A) forests are more productive than grasslands.
B) forests are less productive than grasslands.
C) large mammals avoid living in forests.
D) trees store much of their energy in difficult-to-digest wood, whereas grassland plants produce few difficult-to-digest tissues.
E) grasses grow faster than trees.

Question 16

The species that live and interact in a given area constitute an ecological

A) biome.
B) family.
C) food web.
D) community.
E) trophic level.

Question 17

An ecological community is

A) a group of species that coexist and interact within a defined area.
B) a group of species that coexist and interact in an area together with the abiotic environment.
C) all the species in an area that belong to a particular trophic level.
D) all the species that are members of a local food web.
E) All of the above

Question 18

Which of the following is a primary producer?

A) Spider
B) Earthworm
C) Oak tree
D) Human
E) None of the above

Question 19

Which of the following is a primary consumer?

A) A predatory fish
B) A detritus-eating roundworm
C) An oak tree
D) A herbivorous beetle larva
E) None of the above

Question 20

A trophic level consists of the organisms

A) whose energy has passed through the same number of steps to reach them.
B) that use similar foraging methods to obtain food.
C) that are eaten by a similar set of predators.
D) that eat both plants and other animals.
E) that compete with one another for food.

Question 21

The number of trophic levels in most communities is limited by

A) the presence of decomposers.
B) predation.
C) competitive exclusion.
D) succession.
E) the loss of energy between trophic levels.

Question 22

The reintroduction of wolves into Yellowstone in 1995 had _______ effect on aspen and _______ effect on elk.

A) a direct; a direct
B) a direct; an indirect
C) a direct; no
D) an indirect; a direct
E) an indirect; an indirect

Question 23

Grain is eaten by cows, and cows are eaten by humans. If the ecological transfer efficiency between each trophic level is 10 percent, how much grain is required to produce 70 kg of human biomass?

A) 7 kg
B) 70 kg
C) 700 kg
D) 7,000 kg
E) 70,000 kg

Question 24

The introduction of a large predatory fish into a lake will lead to declines in the populations of smaller fish; this decrease in the smaller fish will lead to an increase in the plankton on which they feed. This phenomenon is called

A) character displacement.
B) keystone exchange.
C) trophic cascade.
D) primary succession.
E) heterotrophic succession.

Question 25

Beavers affect communities by

A) what they eat.
B) altering patterns of vegetation as they preferentially cut down certain trees.
C) creating meadows and ponds by means of their dams.
D) All of the above
E) None of the above

Question 26

Which of the following statements about wolves in Yellowstone National Park is true?

A) They are the only predators of moose and elk.
B) Their disappearance led directly to the severe reduction of young aspen trees.
C) Their disappearance led indirectly to the severe reduction of young aspen trees.
D) Both a and b
E) Both a and c

Question 27

A termite mound alters the environment in such a way that it creates new habitats for a variety of organisms. In constructing these mounds, therefore, termites can be considered

A) a keystone species.
B) trophic cascaders.
C) ecosystem engineers.
D) facilitator species.
E) primary producers.

Question 28

In which of the following communities would one expect to see greater energy flow into primary consumers than into primary producers?

A) Forest
B) Grassland
C) Open ocean
D) All of the above
E) None of the above

Question 29

Which of the following always has a "pyramidal" shape (i.e., decreasing values at higher trophic levels)?

A) Pyramids of number
B) Pyramids of biomass
C) Pyramids of energy
D) Both a and b
E) None of the above

Question 30

In which of the following communities would one expect to see more biomass in primary consumers than in primary producers?

A) Forest
B) Grassland
C) Open ocean
D) All of the above
E) None of the above

Question 31

If gross primary productivity is 120 units per day, and the respiration rate is 30 units per day, net primary productivity is _______ units per day.

A) 4
B) 30
C) 90
D) 120
E) 150

Question 32

Suppose that the gamma diversity for a marshy habitat and the gamma diversity for a sandy habitat are comparable for a particular geographic region, but the alpha diversity for marshy habitats tends to be much greater than the alpha diversity for sandy habitats. We could conclude that

A) beta diversity is higher in marshy habitats.
B) beta diversity is roughly the same in both marshy and sandy habitats.
C) beta diversity is lower in marshy habitats.
D) the Shannon index is higher in marshy habitats, but Sorenson's index is lower.
E) the Shannon index is lower in marshy habitats, but Sorenson's index is higher.

Question 33

In most communities, which of the following is greater in tertiary consumers as compared to secondary consumers?

A) Reproductive rates
B) Number of species
C) Total biomass
D) Body size
E) None of the above

Question 34

For most communities, species richness will _______ if fertilizer is added when productivity is low, and it will _______ if fertilizer is added when productivity is high.

A) increase; increase
B) increase; decrease
C) remain the same; increase
D) decrease; increase
E) decrease; decrease

Question 35

Which of the following resulted from Robert Paine's removing the predator sea star from parts of the intertidal zone?

A) Many species disappeared from the environment.
B) The species richness increased.
C) One species of mussel, Mytilus californianus, benefited.
D) Both a and c
E) Both b and c

Question 36

As productivity increases, species richness in a community

A) generally increases.
B) generally decreases.
C) stays relatively flat.
D) increases at first and then decreases.
E) decreases at first and then increases.

Question 37

Suppose you were going up the west coast of Australia and observed that there are many species of termites in any one community, and the species composition changed little between communities. You would conclude that for these termites,

A) both the alpha and beta diversities are high.
B) the alpha diversity is low, but the beta diversity is high.
C) the alpha diversity is high, and the beta diversity is low.
D) the alpha diversity is high, and the beta diversity is negative.
E) the alpha diversity is low, and the beta diversity is negative.

Question 38

Which of the following factors reduces the efficiency of energy transfer between trophic levels?

A) Lack of availability of some biomass
B) Heat loss
C) Indigestibility of some biomass
D) All of the above
E) None of the above

Question 39

If secondary consumers are the highest trophic level in a community, how many trophic levels are in the community (not counting decomposers)?

A) Two
B) Three
C) Four
D) Three if it is an aquatic community, four if it is a terrestrial community
E) Three if it is a terrestrial community, four if it is an aquatic community

Question 40

A species that exerts an influence on a community that is much greater than its abundance would lead one to expect is called a(n)

A) primary producer.
B) ecosystem engineer.
C) keystone species.
D) successional species.
E) Tilman species.

Question 41

In calculating alpha diversity, the Shannon diversity index measures

A) the absolute abundance of species.
B) the relative abundance of species.
C) the ecological diversity of species.
D) the morphological diversity of species.
E) differences in species composition across habitats or communities.

Question 42

Following a severe ice storm in 1991 in Rochester, New York, the composition of the trees changed as the community recovered from the disturbance. This is an example of

A) competitive succession.
B) primary succession.
C) secondary succession.
D) keystone succession.
E) None of the above

Question 43

Sorenson's index measures _______ diversity.

A) alpha
B) beta
C) functional
D) gamma
E) delta

Question 44

A study of diversity patterns in an agricultural area of southern England showed that rivers have _______ alpha diversity and _______ beta diversity.

A) high; high
B) high; low
C) high; negative
D) low; high
E) low; low

Question 45

According to the island biogeography model, _______ and _______ determine the number of species on an island.

A) climate; vicariant events
B) the size of the island; its distance from the mainland
C) the species pool; the speciation rate
D) the speciation rate; the extinction rate
E) elevation; shape

Question 46

Which of the following is the correct chronological order (from youngest to oldest) for the succession of species in Glacier Park?

A) Alders, spruces, lichens
B) Spruces, alders, lichens
C) Spruces, lichens, alders
D) Lichens, spruces, alders
E) Lichens, alders, spruces

Question 47

One assumption of the theory of island biogeography is that _______ population sizes of species will _______.

A) small; decrease the likelihood of speciation
B) small; increase the likelihood of speciation
C) large; increase the species pool
D) large; decrease the species pool
E) None of the above

Question 48

The island biogeography theory addresses

A) the extent of beta diversity in different biogeographic regions.
B) the latitudinal gradient of species richness.
C) species-area relationships.
D) Both a and b
E) Both a and c

Question 49

Which of the following would most likely be found late in succession?

A) Mostly plants that produce a high number of small seeds
B) Simple food webs
C) Most nutrients present as detritus
D) Plants producing chemicals that interfere with the growth of other plants
E) Mostly plants that are good dispersers

Question 50

Which of the following is a hypothesis generated by biologists to explain species richness gradients?

A) Greater competition in the tropics has led to narrower niches and thus more species in the tropics than elsewhere.
B) The lack of mutualisms in the higher latitudes limits the number of species in high latitude communities.
C) Intense predation in the polar regions limits the number of species that can live there.
D) Both a and b
E) Both b and c

Question 51

Which of the following statements about the patterns of succession in moraines at Glacier Bay is true?

A) We know a great deal about the patterns from detailed observations that have taken place over the past 200 years.
B) The youngest moraines are populated with bacteria, fungi, and photosynthetic microorganisms.
C) The composition of the soil has remained relatively constant over the past 200 years.
D) Nitrogen is highly abundant in young moraines.
E) Both a and b

Question 52

The plants that grow best on recently formed moraines at Glacier Bay are those that

A) grow under conditions of low oxygen.
B) are superior competitors.
C) form mutualisms with nitrogen-fixing bacteria.
D) are highly resistant to herbivores.
E) None of the above

Question 53

Which of the following statements about disturbances is false?

A) They are always caused by biotic factors.
B) They can be beneficial to some species.
C) They can be caused by keystone species.
D) Small disturbances are more common than large ones, but large disturbances have a greater overall effect.
E) All of the above are true; none is false.

Question 54

Which of the following would be most useful for calculating alpha diversity?

A) Sorenson's index
B) The Spicoli index
C) The Shannon index
D) The species-area relationship
E) The successional integral

Question 55

In one community, 10 species of grasses are found. A nearby community has 15 species, and shares 6 of those species with the first community. What is Sorenson's index for these communities?

A) 0.24
B) 0.4
C) 0.48
D) 0.6
E) 0.8

Question 56

Daniel Simberloff and Edward Wilson tested the island biogeography theory by

A) releasing animals on oceanic islands.
B) defaunating tiny islets of mangroves in the Florida Keys.
C) observing the results of the Krakatau volcano explosion.
D) reconstructing phylogenetic relationships of horses.
E) None of the above

Question 57

Which of the following statements about species richness is true?

A) It is highest in the temperate zone in both hemispheres.
B) It is highest in the Northern temperate zone, followed by the tropics, followed by the Southern temperate zone.
C) It is highest in the tropics.
D) It is highest in the Southern temperate zone, followed by the tropics, followed by the Northern temperate zone.
E) None of the above

Question 58

Which of the following statements about island biogeography is false?

A) Major disturbances can serve as "natural experiments" that allow researchers to estimate colonization rates.
B) When species numbers are above the equilibrium, island biogeography theory predicts that extinction rates will increase.
C) When species numbers are far below the equilibrium, island biogeography theory predicts that immigration rates will increase.
D) The theory of island biogeography is particularly concerned with the identity of species found at particular islands.
E) All of the above are true; none is false.

Question 59

Three species of grasshoppers are found in a transect: 10 of species A, 15 of species B, and 25 of species C. What is the Shannon diversity index of this transect? (Note: * = times, and ln (x) is the natural logarithm of x.)

A) [0.1 * ln (0.1)] + [0.15 * ln (0.15)] + [0.25 * ln (0.25)]
B) [10 * ln (10)] + [15 * ln (15)] + [25 * ln (25)]
C) The negative of { [10 * ln (10)] + [15 * ln (15)] + [25 * ln (25)]}
D) The negative of { [0.1 * ln (0.1)] + [0.15 * ln (0.15)] + [0.25 * ln (0.25)]}
E) The negative of { [0.2 * ln (0.2)] + [0.3 * ln (0.3)] + [0.5 * ln (0.5)]

Question 60

Which of the following statements about succession is false?

A) Facilitation plays an important role in succession.
B) Inhibition plays an important role in succession.
C) As succession proceeds, K-strategy plants are replaced by r-strategy plants.
D) Food webs increase in complexity during succession.
E) All of the above are true; none is false.

Question 61

In Tilman's experiments, _______ declined as species richness increased.

A) productivity
B) species turnover
C) the amount of nitrogen left in the soil
D) All of the above
E) None of the above

Question 62

The presence of soil fauna increases the likelihood that many plants will be established during succession. This is an example of

A) disturbance.
B) facilitation.
C) recruitment.
D) reinforcement.
E) inhibition.

Question 63

Which of the following studies have been helpful in answering questions regarding the use of monocultures?

A) Those on the effects of restoring wolves to Yellowstone
B) Robert Paine's studies of keystone species in the rocky intertidal zones
C) Simberloff and Wilson's experiments testing island biogeography models in the Florida Keys
D) Those examining patterns of the succession in Glacier Bay
E) Tilman's studies examining the relationship between species richness and community stability

Question 64

Most species of spiders eat plant-eating insects. Spiders are thus primary _______, or secondary _______.

Question 65

David Tilman's experiments showed that as species richness increases, productivity _______ and the variation in productivity _______.

A) decreases; increases
B) decreases; remains constant
C) decreases; decreases
D) increases; increases
E) increases; decreases

Question 66

The extinction of a predatory bird leads to an increase in the population size of a small mammal, which in turn leads to a decrease in the population size of the plants on which the mammal feeds. This is an example of a _______, which is caused by a series of _______ effects.

Question 67

Many species of birds eat plants as well as other animals. They thus belong to the _______ trophic level.

Question 68

The first phase of decomposition is

A) dry decay.
B) autolysis.
C) primary succession.
D) wet decay.
E) putrefaction.

Question 69

Cows, which eat grass and other plant materials, belong to the _______ trophic level.

Question 70

Earthworms feed off of dead material and are thus considered _______.

Question 71

The species that live and interact in a particular area constitute an ecological _______.

Question 72

In the open ocean, the biomass of a community is usually highest at the _______ trophic level because the _______ have a high reproductive rate.

Question 73

If 640 units of energy move through the primary producers of a community and 128 units move through the primary consumers, then the ecological efficiency is _______.

Question 74

If gross primary productivity is 309 units and the respiration rate is 147 units, then net primary productivity is _______ units.

Question 75

In the lodgepole pine community, periodic disturbances occur in the form of

A) floods.
B) fire.
C) beetle infestations.
D) fungal infections.
E) predators.

Question 76

The reintroduction of wolves into Yellowstone in 1995 caused a decrease in the population of _______. This decline enabled aspen seedlings to become reestablished.

Question 77

Which of the following represents the correct chronological order (from earliest to latest) in which the organisms below appear on a dead body?

A) Spider beetles, blowflies, flesh flies
B) Spider beetles, flesh flies, blowflies
C) Blowflies, flesh flies, spider beetles
D) Flesh flies, blowflies, spider beetles
E) Flesh flies, spider beetles, blowflies

Question 78

Although ecologists often diagram the interactions of who eats whom by means of a food chain, depicting the complexity of real-life interactions often requires the construction of a _______.

Question 79

Tilman's experiments showed that increasing species richness enhanced community stability because

A) it increased the stability of each species' performance.
B) different species performed better under different environmental circumstances.
C) it increased the likelihood of predation.
D) more nutrients remained in the soil in communities with few species.
E) None of the above; increasing species richness did not enhance community stability.

Question 80

Species such as beavers, which create structures in the environment that serve as habitat for other species, are called _______.