chapter 18 Flashcards

1
Q

an assemblage of species living together in an area

A

community

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Community zonation also occurs in

A

aquatic communities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Communities are often categorized by their

A

dominant organisms or by physical conditions that affect the distribution of species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Aquatic systems are often categorized by

A

physical characteristics (e.g., stream or lake communities) or by dominant organisms (e.g., coral reef communities).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ecologists rarely study every species in a community; rather, they

A

focus on a subset of species that live in an area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

a boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species.

A

Ecotone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Some species move between

A

adjacent communities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

most species live in

A

one of the communities and spread into the ecotone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Ecotones support a large number of species

A

including those from adjoining habitats, and species specifically adapted to the ecotone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

communities in which species depend on each other to exist.

A

Interdependent communities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

communities in which species do not depend on each other to exist.

A

Independent communities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

If species are interdependent, removing a species should cause

A

other species to decline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

if species are independent, removing a species should cause

A

neutral or positive changes in other species’ fitness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

the # of species in a community.

A

Species richness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

the proportion of individuals in a community represented by each species.

A

Relative abundance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In a typical community, only a few species have

A

low or high abundance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

most species have intermediate

A

abundance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

if a species has intermediate abundance they follow a

A

log normal distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

a curve that plots the relative abundance of each species in a community in rank order from the most abundant species to the least abundant species.

A

Rank-abundance curves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

a comparison of the relative abundance of each species in a community.

A

Species evenness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The species richness of a community can be affected by

A

the amount of available resources.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

To understand the influence of resources, ecologists have examined the relationship between

A

productivity and species richness.

23
Q

observed patterns across aquatic and terrestrial environments

A
u shaped 
negative 
neutral 
positive
hump shaped
24
Q

what is the most commonly observed relationship between diversity and productivity

A

hump shaped curve

25
Q

Experiments have manipulated productivity by

A

adding nutrients (e.g., nitrogen) to an ecosystem.

26
Q

Added fertility commonly causes a decline in the species richness of

A

producers (e.g., plants and algae).

27
Q

The reason species richness declines with increased habitat fertility

A

is unclear.

28
Q

For plant communities, increased fertility may cause

A

dominant plants to cast more shade on competitively inferior plants.

29
Q

Communities with a higher diversity of habitats should offer

A

more potential niches (e.g., places to feed and breed) and a higher diversity of species.

30
Q

a species that substantially affects the structure of communities, although species might not be particularly numerous

A

Keystone species

31
Q

Removal of a keystone species can cause

A

a community to collapse

32
Q

keystones species that affect communities by influencing the structure of a habitat.

A

Ecosystem engineers

33
Q

the hypothesis that more species are present in a community that experiences occasional disturbances than in a community with either frequent or rare disturbances.

A

Intermediate disturbance hypothesis

34
Q

When disturbances are rare, populations

A

grow until resources are scarce, and competitively superior species become dominant

35
Q

When disturbances are frequent, habitats

A

typically support a small number of species that are adapted to disturbances.

36
Q

When disturbances occur at an intermediate frequency,

A

both types of species can persist

37
Q

a linear representation of how different species in a community feed on each other.

A

Food chain

38
Q

a complex and realistic representation of how species feed on each other in a community.

A

Food web

39
Q

a level in a food chain or food web of an ecosystem.

A

Trophic level

40
Q

the autotrophs that convert light energy and CO2 into carbohydrates through photosynthesis.

A

Producers

41
Q

a species that eats producers.

A

Primary consumer

42
Q

a species that eats primary consumers

A

Secondary consumer

43
Q

a species that eats secondary consumers

A

Tertiary consumer

44
Q

a species that feeds at several trophic levels.

A

Omnivore

45
Q

within a given trophic level, a group of species that feeds on similar items (e.g., guilds of leaf eaters); members of the group are not necessarily related

A

Guild

46
Q

an interaction between two species that does not involve other species

A

Direct effect

47
Q

The direct effect of one species often sets off a chain of events that

A

affect other species in the community

48
Q

an interaction between two species that involves one or more intermediate species.

A

Indirect effect

49
Q

indirect effects in a community that are initiated by a predator.

A

Trophic cascade

50
Q

Indirect effects can occur

A

between communities.

51
Q

when the abundances of trophic groups are determined by the amount of energy available from producers

A

Bottom-up control

52
Q

when the abundances of trophic groups are determined by the existence of predators at the top of the food web

A

Top-down control

53
Q

If food webs have three trophic levels, top-down control by predators would

A

reduce the abundance of herbivores, leading to an increase in vegetation.

54
Q

researchers (Hairston, Slobodkin, and Smith) suggested that since communities contain an abundance of vegetation

A

food webs must be controlled from the top-down.