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ECOLOGY LECT > Community Ecology > Flashcards

Community Ecology Flashcards

(68 cards)

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1
Q

Key points of Community Ecology

A

A community’s structure can be described by its species richness, and species diversity

Community structure is influenced by many factors, including abiotic factors, species interactions, level of disturbance, and chance events.

Some species, such as foundation species and keystone species, play particularly important roles in determining their communities structure.

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2
Q

Number of species present

A

Species richness

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3
Q

A measure of both species richness and species evenness (relative numbers)

A

Species diversity

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4
Q

Is the feeding relationships between organisms in a community.

A key factor in community dynamics.

A

Trophic structure

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5
Q

Link trophic levels from producers to top carnivores

A

Food chains

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6
Q

Terrestrial food chain (5)

A

Plant - Primary producers

Herbivore - Primary consumers

Carnivore - Secondary consumers

Carnivore - Tertiary consumers

Carnivore - Quarternary consumers

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7
Q

Marine food chain

A

Phytoplankton - Primary producers

Zooplankton - Primary consumers

Carnivore - Secondary consumers

Carnivore - Tertiary consumers

Carnivore - Quarternary consumers

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8
Q

A branching food chain with complex trophic interactions

A

Food web

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9
Q

T or F: Species may play a role at MORE than ONE trophic level

A

True

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10
Q

Food webs can be simplified by (2)

A

Grouping species with similar trophic relationships into broad functional groups

Isolating a portion of a community that interacts very little with the rest of the community

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11
Q

T or F: Each food chain in a food web is multiple links long

A

False, a food web is usually only a FEW links long

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12
Q

Hypotheses attempting to explain food chain length (2)

A

Energetic hypothesis

Dynamic stability hypothesis

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13
Q

Suggests that length is limited by inefficient energy transfer

Example, a producer level consisting of 100 kg of plant material can support about 10 kg of herbivore biomass

A

Energetic hypothesis

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14
Q

Proposes that long food chains are less stable than short ones

A

Dynamic stability hypothesis

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15
Q

The total mass of all individuals in a population

A

biomass

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16
Q

T or F: most data support the dynamic stability hypothesis

A

False, most data support the energetic hypothesis

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17
Q

Are those that are most abundant or have the highest biomass

Exert powerful control over the occurence and distribution of other species

A

Dominant species

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18
Q

Example of Dominant Species (1)

A

Sugar maples
- have a major impact on shading and soil nutrient availability in eastern North America; affects the distribution of other plant species

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19
Q

Two hypotheses on dominant species (2)

A

-Suggests that dominant species are most competitive in exploiting resources

-Suggest that they are most successful at avoiding predators

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20
Q

Typically introduced to a new environment by humans, often lack predators or disease

A

Invasive species

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21
Q

Exert strong control on a community by their ecological roles, or niches

A

Keystone species

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22
Q

T or F: Like dominant species, it is necessary for a keystone species to be abundant in a community

A

False, they are not necessarily abundant in a community

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23
Q

A Keystone species in intertidal communities (1)

A

Sea stars

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24
Q

An event that changes a community

Removes organisms from a community

Alters resource availability

A

Disturbance

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25
Is a significant disturbance in most terrestrial ecosystems Is often a necessity in some communities
Fire
26
Suggests that moderate levels of disturbance can foster higher species diversity than low levels of disturbance
The intermediate disturbance hypothesis
27
Demonstrated that communities can often respond very rapidly to a massive disturbance
Large-scale fire in yellowstone national park in 1988
28
Prairie fire progression (3)
a) BEFORE A CONTROLLED BURN a prairie that has not burned for several years has a high proportion of DETRITUS (dead grass) b)DURING THE BURN detritus serves as fuel for the fires c) AFTER THE BURN approximately one month after the controlled burn, virtually all of the biomass in the prairie is living
29
Large-scale fire in Yellowstone National Park progression (2)
a) SOON AFTER FIRE the burn left a patchy landscape b) ONE YEAR AFTER FIRE A variety of herbaceous plants, different from those in the former forest, cover the ground.
30
Are the most widespread agents of disturbance
Humans
31
Humans disturbance to communities : ___ Humans also prevent some naturally occuring disturbances : ___
Usually reduces species diversity Which can be important to community structure
32
Is the sequence of community and ecosystem changes after a disturbance
Ecological succession
33
Types of ecological succession (2)
Primary succession – Occurs where no soil exists when succession begins Secondary succession – Begins in an area where soil remains after a disturbance
34
May facilitate the appearance of later species by making the environment more favorable May inhibit establishment of later species May tolerate later species but have no impact on their establishment
Early-arriving species
35
Provide a valuable field-research opportunity on succession
Retreating glaciers
36
Follows a predictable pattern of change in vegetation and soil characteristics
Succession on the moraines in Glacier Bay, Alaska
37
Succession on the moraines in Glacier Bay, Alaska (4)
a) pioneer stage, with firewood dominant b) Dryas stage c) Spruce stage d) Nitrogen fixation by Dryas and alder increases the soil nitrogen content
38
Two key factors correlated with a community's species diversity
Geographic loaction and its size
39
Two key factors in equatorial-polar gradients of species richness
Evolutionary history Climate
40
Species richness generally declines along an ___ and is especially great in the tropics
equatorial-polar gradient
41
May account for the greater species richness of tropical environments
The greater age of tropical environments
42
Is likely the primary cause of the latitudinal gradient in biodiversity
Climate
43
two main climatic factors correlated with biodiversity
solar energy input and water availability
44
quantifies the idea that – All other factors being equal, the larger the geographic area of a community, the greater the number of species
species-area curve -supported by the species-curve of North American birds
45
Every organism has a ___ and a ___.
Habitat, Niche
46
A ___ is all aspects of the area in which an organism lives.
habitat
47
An ___ includes all of the factors that a species needs to survive, stay healthy, and reproduce.
ecological niche
48
Under habitat (2)
biotic factors abiotic factors
49
Under ecological niche (2)
-food – abiotic conditions – behavior
50
___ gives structure to a community.
Resource availability
51
occurs when two species use resources in the same way.
competition
52
keeps two species from occupying the same niche.
Competitive exclusion
53
Competitive exclusion has different outcomes (3)
– One species is better suited to the niche and the other will either be pushed out or become extinct. – The niche will be divided. – The two species will further diverge.
54
___ are species that occupy similar niches but live in different geographical regions.
Ecological equivalents
55
is the variety of organisms that make up the community
Species diversity
56
Is the total number of different species in the community
Species richness
57
Is the proportion each species represents of the total individuals in the community
Relative abundance
58
T or F: Two communities can have the same species richness but a different relative abundance
True
59
Diversity can be compared using a ___
diversity index (Shannon diversity index (H))
60
Shannon diversity index (H)
H = –(pA ln pA + pB ln pB + pC ln pC + …) where A, B, C . . . are the species, p is the relative abundance of each species, and ln is the natural logarithm
61
can be used to help determine microbial diversity
Molecular tools
62
T or F: Ecologists abstain from manipulating diversity in experimental communities to study the potential benefits of diversity
False: Ecologists manipulate diversity in experimental communities to study the potential benefits of diversity
63
Example of Ecologists manipulating diversity
For example, plant diversity has been manipulated at Cedar Creek Natural History Area in Minnesota for two decades
64
Communities with higher diversity are (3)
* More productive and more stable in their productivity * Better able to withstand and recover from environmental stresses * More resistant to invasive species, organisms that become established outside their native range
65
Succession regenerates or creates a community after a disturbance (3)
* a sequence of biotic changes * damaged communities are regenerated * new communities arise in previously uninhabited areas
66
Why does change or succession occur? (2)
autogenic processes (associated with the living community) allogenic processes (associated with the physical environment)
67
Different name for secondary natural succession
AUTOREGENERATION
68
Autogenic succession - result of three major biotic mechanisms:
1) Colonization 2)Alteration of the physical characteristics of the site 3) Displacement of species by competition or antibiosis.

ECOLOGY LECT (12 decks)

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