21: Species and Community Interaction

Question 1

A ____ is defined as all of the organisms that live in one location.

Answer 1

Community

Question 2

True or false:

Like with populations, it is difficult to define the borders of a community.

Answer 2

True

Question 3

List four things that can be used to characterize communities.

Answer 3

1. Species within them
2. Species richness
3. Species diversity
4. Primary productivity

Question 4

____ describes the amount of energy produced by a community.

Answer 4

Primary productivity

Question 5

True or false:

A community is a static entity.

Answer 5

False

It can change over space and time

Question 6

True or false:

Species within a community can change independently of one another.

Answer 6

True

Question 7

It can be difficult to predict changes in communities because…

Answer 7

Organisms respond to numerous factors in different ways

Question 8

An organism’s ____ is the total of all the ways that an organism uses the resources in its environment.

Answer 8

Niche

Question 9

List three things that can be used to describe a species’ niche.

Answer 9

1. Food consumption
2. Temperature range
3. Moisture requirements

(not an exhaustive list)

Question 10

In a(n) ____, each factor that determines a species’ niche is treated as one axis of a graph.

Answer 10

N-dimensional hypervolume

Question 11

The entire niche that a species is capable of using is called their…

Answer 11

Fundamental niche

Question 12

The actual niche that a species is occupying as a result of interactions between different species is called its…

Answer 12

Realized niche

Question 13

The realized niche is ____ than the niche the species would occupy if there were no other species present.

Answer 13

Smaller

Question 14

____ can affect a species’ realized niche.

Answer 14

Interspecific competition

Question 15

____ occurs when there is physical interaction between species over a resource.

Answer 15

Interference competition

Question 16

____ occurs when one species uses a resource and thereby prevents another species from using that resource.

Answer 16

Exploitative competition

Question 17

____ was originally defined as occurring when two species compete for a limited resource and the species that is more efficient at using that resources drives the other to extinction in the area.

Answer 17

Competitive exclusion

Question 18

True or false:

Some species can coexist even if their niches overlap.

Answer 18

True

Question 19

Today, competitive exclusion means that…

Answer 19

No two species can occupy identical niches forever when resources are limited

Question 20

List three factors that may allow species whose niches overlap to coexist.

Answer 20

1. Their niches are not identical
2. Resources are not limited
3. Environmental changes change which species is favored often enough that the other is not driven to extinction

Question 21

When competitive exclusion occurs, the two species might subdivide their niche, a process called…

Answer 21

Resource partitioning

Question 22

When resource partitioning occurs, the species evolve so that…

Answer 22

Their niches don’t overlap as much

Question 23

____ occurs when competing species evolve so they are less similar to each other, thus enhancing resource partitioning.

Answer 23

Character displacement

Question 24

____ decreases niche overlap by allowing each species to specialize in different areas of the niche.

Answer 24

Character displacement

Question 25

Niche theory suggests that ____ and ____ are natural consequences of competition when each species is better able to dominate one part of the niche.

Answer 25

Resource partitioning and character displacement

Question 26

____ is a competing idea to niche theory.

Answer 26

Neutral theory

Question 27

____ often have strong impacts on prey population sizes.

Answer 27

Predators

Question 28

The sudden addition or removal of predators can cause...

Answer 28

Prey populations to crash or explode

Question 29

List two non-lethal effects that predators may have on prey.

Answer 29

1. Prey avoid the most dangerous areas, affecting their ability to gather food 2. Prey may be under stress, decreasing their ability to reproduce

Question 30

The presence of predators affects prey evolution by...

Answer 30

Creating a strong selection for individuals that can evade or avoid predators

Question 31

____ occurs when every advance in prey evolution leads to advances in predator evolution.

Answer 31

Coevolution

Question 32

List two adaptations that plants may use to defend themselves against herbivores.

Answer 32

1. Morphological defenses 2. Chemical defenses

Question 33

List three types of morphological defenses found in plants.

Answer 33

1. Thorns and spikes 2. Hairs and sticky secretions 3. Silica deposits in soft tissues

Question 34

Chemical defenses in plants take the form of...

Answer 34

Secondary chemical compounds (secondary metabolites)

Question 35

List four adaptations found in animals to defend against predators.

Answer 35

1. Secondary compounds in diet 2. Chemical defenses 3. Defensive coloration 4. Mimicry

Question 36

Some animals ingest ____, toxic substances that poison any animal that eats them.

Answer 36

Secondary compounds

Question 37

The ____ produced by poison dart frogs are an example of chemical defenses in animals.

Answer 37

Defensive alkaloids

Question 38

List two types of defensive coloration that animals may have.

Answer 38

1. Warning coloration 2. Cryptic coloration

Question 39

____ describes showy colors and patterns that advertise that the animal has chemical defenses.

Answer 39

Warning coloration

Question 40

____ describes colors and patterns that allow the animal to blend in with its surroundings.

Answer 40

Cryptic coloration

Question 41

____ allows a species to capitalize on the warning coloration of another species.

Answer 41

Mimicry

Question 42

List the two types of mimicry.

Answer 42

1. Batesian mimicry 2. Mullerian mimicry

Question 43

____ occurs when a species that has no defensive chemicals mimics the appearance of a species that does.

Answer 43

Batesian mimicry

Question 44

____ occurs when two or more species with chemical defenses resemble each other.

Answer 44

Mullerian mimicry

Question 45

How does Mullerian mimicry protect animals from predators?

Answer 45

Because several species look similar, the predator only has to learn one species' appearance to avoid all the species

Question 46

____ refers to any relationship that evolves between species over time.

Answer 46

Symbiosis

Question 47

List three types of symbiotic relationships.

Answer 47

1. Mutualism 2. Parasitism 3. Commensalism

Question 48

____ occurs when both species benefit from the relationship.

Answer 48

Mutualism

Question 49

If one species in a mutualistic relationship gains the upper hand, the relationship may become...

Answer 49

Parasitic

Question 50

____ occurs when one species benefits from the relationship and the other is harmed.

Answer 50

Parasitism

Question 51

Parasites that live inside their hosts are called...

Answer 51

Endoparasites

Question 52

Parasites that live on or outside their hosts are called...

Answer 52

Ectoparasites

Question 53

Insects that lay their eggs in or on other organisms are called...

Answer 53

Parasitoids

Question 54

Parasites may cause changes in their host's brain or behavior to...

Answer 54

Improve chances of the host transmitting the parasite

Question 55

____ occurs when one species benefits from the relationship and the other is unaffected.

Answer 55

Commensalism

Question 56

Predation can reduce competition among prey species by...

Answer 56

Lowering the number of animals competing for a limited food source

Question 57

If one prey species is a better competitior, its abundance may make it a greater target for predators, which...

Answer 57

Prevents a population explosion that could drive other competitors extinct

Question 58

# True or false: Eliminating a major predator may decrease diversity among prey species.

Answer 58

True

Question 59

____ affects competition by having different effects on competing species.

Answer 59

Parasitism

Question 60

____ occur when two species affect each other through another species.

Answer 60

Indirect effcts

Question 61

# True or false: A species can simultaneously have a direct negative effect and an indirect positive effect on another species.

Answer 61

True

Question 62

____ are species whose effects on the composition of their communities is far greater than would be expected given that species' abundance.

Answer 62

Keystone species

Question 63

Top predators are often ____ in their communities.

Answer 63

Keystone species

Question 64

____ is the tendency of communities to change from simple to complex over time.

Answer 64

Ecological succession

Question 65

Ecological succession involves a change in the ____ of the community.

Answer 65

Species composition

Question 66

____ occurs when a biological community develops from completely bare substrate.

Answer 66

Primary succession

Question 67

____ occurs when a community is destroyed, but some species survive to create a new community.

Answer 67

Secondary succession

Question 68

List the three phases of ecological succession.

Answer 68

1. Establishment 2. Facilitation 3. Inhibition

Question 69

During the ____ phase of succession, the area is populated by weedy, R-selected organisms.

Answer 69

Establishment

Question 70

An organism that is "weedy" is one that...

Answer 70

Can survive in harsh conditions

Question 71

During the ____ phase of succession, weedy organisms cause changes in the environment that make it more suitable for K-selected species.

Answer 71

Facilitation

Question 72

During the ____ phase of succession, the K-selected species inhibit the R-selected species that originally changed the habitat.

Answer 72

Inhibition

Question 73

During the process of succession, ____ first increases for a long period of time.

Answer 73

Species richness

Question 74

During the process of succession, species richness will eventually decline as...

Answer 74

K-selected species replace R-selected species

Question 75

The process of ecological succession may eventually result in a decline in species richness because...

Answer 75

Superior competitiors prevent others from surviving

Question 76

The growth of a biological community on a new volcanic island is an example of...

Answer 76

Primary succession

Question 77

The regrowth of a biological community after a forest fire is an example of...

Answer 77

Secondary succession

Question 78

____ are events that a community experiences that can affect its species richness.

Answer 78

Disturbances