Deck 17: Factors Influencing the Structure of Communities

Question 1

Variation in environmental conditions within a community is referred to as environmental ________.

Answer 1

heterogeneity

Question 2

________ or functional groups are groups of species in a community that are thought to have similar roles in the community.

Answer 2

Guilds

Question 3

Patterns of temperature and ________ resulting from regional variations in climate are the major determinant of regional and global patterns of vegetation distribution.

Answer 3

moisture

Question 4

________ predation is a type of indirect interaction in which a predator enhances the success of one or more inferior competitors by reducing the abundance of a superior competitor.

Question 5

When interspecific interactions involve more than just two species,they are said to be ________.

Question 6

________ competition is a type of indirect interaction that occurs when a single species of predator feeds on two prey species.

Question 7

In comparison to the upper intertidal zone,species in the lower intertidal zone are more apt to

A)be desiccation tolerant.
B)have a lower metabolic rate.
C)have lower resource requirements.
D)be better competitors.

Question 8

Considerable evidence indicates that the null model of community structure is incorrect because

A)each species responds independently of other species to the prevailing physical environment.
B)interactions among species have no significant influence on community structure.
C)when one species is removed,the populations of the other species are unaffected.
D)species interactions modify the fundamental niche of the species involved,influencing their relative abundance and,in some cases,their distribution.

Question 9

Which of the following is evidence against the null model?

A)Bristlecone pine trees can survive harsh winters.
B)Climate change alters abundance of robins.
C)Invasive species cause California newts to go locally extinct.
D)Hurricanes can wipe out fauna on an island.

Question 10

Which of the following is an example of a fundamental niche?

A)a mouse feeding on only small seeds in the presence of a competitor
B)an amphibian laying eggs in all possible habitats
C)a bird nesting on top of a tree in the presence of predators
D)a lizard feeding on insects only at dawn when snakes are present

Question 11

What might one expect to see in a graph depicting realized niche space in a community?

A)one dominant species utilizing all of the resources
B)large overlap between species resource use
C)reduced overlap between species resource use
D)each species utilizing its full resources

Question 12

A(n)________ model of community structure assumes that the presence and absence of individual species in a community result from independent responses to the physical environment and interactions among species have no impact on community structure.

Question 13

When an indirect interaction is beneficial to one of two interacting species and neutral to the other,the indirect interaction is termed indirect ________.

Question 14

In aquatic environments,the three major environmental gradients of water that directly influence the distribution and dynamics of communities include

A)temperature,depth,and oxygen content.
B)depth,flow rate,and salinity.
C)pressure,temperature,and depth.
D)flow rate,salinity,and oxygen content.

Question 15

When prey populations are controlled by predators in a trophic level above them,they are said to be under ________ control.

Question 16

In looking at a distribution map you see an empty space where habitat conditions are suitable for that species.Why might that exist?

A)Other species outcompete it in that space.
B)That species prefers other areas.
C)The species has a limit to population growth.
D)The space is due to the null model.

Question 17

The ________ is a group of plant and animal species that inhabits a given area.

Question 18

In all experimental studies to date,the effect of increasing nutrient availability to plants has been to ________ plant diversity.

Question 19

Plant community structure along an environmental gradient can often be explained by

A)differences among species in their competitive abilities.
B)differences among species in their abilities to tolerate stress.
C)differences among species in their resistance to herbivores.
D)a trade-off among species with respect to competitive ability and stress tolerance.

Question 20

What happens to the species Chthamalus stellatus when Balanus balanoides is removed from the lower intertidal zone?

A)Chthamalus is able to survive in the lower intertidal zone.
B)Chthamalus survives worse.
C)Balanus switches habitat to the upper intertidal zone.
D)There is no change in distribution for either species.

Question 21

The "world is green" hypothesis advocates which mechanism?

A)bottom-up control
B)top-down control
C)the null model
D)diffuse competition

Question 22

Increasing the resources for one species results in the increase of predator numbers.This reduces the abundance of another prey species.This interaction is

A)indirect commensalism.
B)indirect mutualism.
C)apparent competition.
D)apparent predation.

Question 23

Removal of sea otters from a system results in a massive increase in sea urchins and subsequent loss of kelp beds.This is an example of

A)a trophic cascade.
B)apparent competition.
C)bottom-up control.
D)indirect mutualism.

Question 24

When bass were removed from a stream,an algal bloom occurred.This is an example of

A)top-down control.
B)bottom-up control.
C)the null model.
D)apparent competition.

Question 25

What does this figure suggest?

A)Decreased foliage height diversity drives increased bird diversity.
B)Increased foliage height diversity drives increased bird diversity.
C)There is no relationship between foliage height and bird diversity.
D)Increased bird diversity drives increased foliage height diversity.

Question 26

As the degree of environmental heterogeneity of a community increases,the number of plant and animal species tends to

A)decrease.
B)remain the same.
C)increase.
D)increase initially and then decrease.

Question 27

What is a misconception about the Canada lynx and snowshoe hare cycling?

A)Canada lynx are the only predators on snowshoe hares.
B)Snowshoe hares impact resource abundance.
C)Snowshoe hare populations vary over time.
D)Rodents compete with snowshoe hares for grasses.

Question 28

Which is an example of a diffuse species interaction?

A)Removal of one beetle species from a community shows no effect.
B)Canada lynx cause population cycling in snowshoe hares.
C)Removal of sea otters results in kelp forest depletion.
D)Loss of starfish results in mussel outcompeting other species.

Question 29

A diffuse species interaction infers the effects of

A)predation by one species on another is strong.
B)competition by one species on another is strong.
C)competition by one species on another is weak.
D)predation is stronger than those of competition.

Question 30

What is the term when one species benefits from an indirect interaction and the other has a neutral effect?

A)indirect competition
B)indirect mutualism
C)mutualism
D)indirect commensalism

Question 31

Which of the following communities could exhibit apparent competition?

A)species that share a predator but not resources
B)species the share resources but not a predator
C)species that do not share either resources or a predator
D)species with diffuse interactions

Question 32

Given large differences in moisture retention in soils,what would you predict?

A)decreased community diversity
B)no effect on community diversity
C)increased community diversity
D)more similar functional types in the community

Question 33

Why might biologists assemble species into functional groups when examining community structure?

A)to better focus on species by species interactions
B)to fit the null model
C)to understand the significance of a single species by assembling them in functional groups
D)to understand functional types because individual species might not be as significant

Question 34

A competitive plant growing in wet conditions would be predicted to have

A)a larger root system.
B)high tolerance to water stress.
C)low metabolic rate.
D)many leaves and stems.

Question 35

Which of the following is considered a keystone predator?

A)mussels
B)starfish
C)kelp bed
D)kelp bass

Question 36

Spartina alterniflora allocates more ________ to outcompete Juncus gerardi.

A)carbon to root biomass
B)carbon to leafs
C)nutrients to herbivores
D)water to root biomass

Question 37

When top-down control occurs within an intertidal zone along the rocky coastline of the Pacific Ocean,which of the following species controls the abundance of other species?

A)kelp
B)mussels
C)barnacles
D)starfish

Question 38

When apparent competition occurs,the

A)populations of predator and prey species are smaller.
B)population of the predator species is larger and the populations of the prey species are smaller.
C)population of the predator species is smaller and the populations of the prey species are larger.
D)populations of predator and prey species are larger.

Question 39

Food webs are typically arranged into trophic levels with

A)primary producers at the bottom,herbivores in the middle,and carnivores at the top.
B)herbivores at the bottom,carnivores in the middle,and primary producers at the top.
C)carnivores at the bottom,herbivores in the middle,and primary producers at the top.
D)primary producers at the bottom,carnivores in the middle,and herbivores at the top.

Question 40

Experiments on competition among species within a community reveal that

A)removing a group of species has relatively little effect on a community.
B)removing a single species has a stronger effect than removing a group of species from a community.
C)removing a group of species has a stronger effect than removing a single species from a community.
D)removing a single species has relatively little effect on a community.

Question 41

Environmental conditions often vary spatially but do not tend to change over time in a given place.

Question 42

Which of the following organisms have benefited from wolf reintroduction?

A)grizzly bears
B)beavers
C)woody plant species
D)all of the above

Question 43

As the fertility of soil on the forest floor increases,the

A)growth rate of plants increases.
B)size of plants decreases.
C)density of plants decreases.
D)number of species of plants increases.

Question 44

The "world is green" hypothesis suggests that herbivore populations limit the number of predators,allowing plant biomass to accumulate.

Question 45

The diversity of an animal community is unrelated to the physical structure of a plant community.

Question 46

Within a community,most species have a similar range of environmental tolerances.

Question 47

In Yellowstone National Park,the reintroduction of wolves has led to

A)increased fruit consumption in elk.
B)a decrease in deciduous tree growth.
C)a decrease in the elk population.
D)an increase in the elk population.

Question 48

Species interactions within a community rarely involve only two species.

Question 49

This figure suggests that adding more and more nutrients over time will result in

A)an increase in species diversity.
B)an increase in species evenness.
C)a decrease in overall productivity.
D)a decrease in species diversity.

Question 50

Diffuse interactions often occur among competing species but never among predator-prey species.

Question 51

Competitive interactions are often diffuse,whereas mutualisms are not.

Question 52

Competition among plant species rarely involves only a single resource.

Question 53

The control of an herbivore population by a parasitoid is an example of top-down control.

Question 54

Why might increased soil fertility result in lower species diversity?

A)There is no relationship between soil fertility and species diversity.
B)Increased nutrients help more rare plants survive.
C)Dominant species are better able to outcompete other species.
D)Dominant species are less able to outcompete other species.

Question 55

Indirect interactions can be either positive or negative for the affected species.

Question 56

The populations of keystone predators are controlled by the populations of their prey species.

Question 57

There is considerable evidence that community structure is influenced by interactions between species.

Question 58

Why might increased nutrient availability result in increased species diversity in aquatic systems while it results in decreases in terrestrial systems?

A)Aquatic systems have weaker competitive interactions.
B)Aquatic systems have stronger competitive interactions.
C)Nutrients are diluted too rapidly in aquatic systems.
D)Nutrients are always abundant in terrestrial systems.

Question 59

Environmental heterogeneity tends to be positively correlated with species diversity.

Question 60

The removal of a single species from a community can have unpredictable consequences.

Question 61

In aquatic communities,an increase in nutrients usually causes the number of autotrophic species to increase.

Question 62

Competition for belowground resources is considered to be asymmetric because larger plants have a disproportionate advantage in competition for those resources.