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BIOL 360 - General Ecology > Community (Diversity, Structure, Disturbance) > Flashcards

Community (Diversity, Structure, Disturbance) Flashcards

1
Q

Disturbance

A

an event of intense environmental stress occurring over a relatively short period of time and causing large changes in the affected ecosystem

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2
Q

Intermediate disturbance hypothesis

A

Species diversity will be highest in communities that experience intermediate levels of disturbance

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3
Q

Community

A

an association of interacting species inhabiting some defined area

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4
Q

Community structure

A

Based on the INTERACTIONS of all species in a community.

How abiotic & biotic factors influence the number of species, relative abundance of species, and the types of species in an area

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5
Q

Guild

A

One type of organism that make their living the same way

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6
Q

How abundant are most species?

A

Moderately abundant.

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7
Q

Species richness

A

Number of species in a community

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8
Q

Species evenness

A

Relative abundance of species

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9
Q

What are metrics we can use to describe community diversity?

A

(1) Species richness
(2) Species evenness
(3) Shannon-Wiener index (H’)
(4) Simpson Index (y)
(5) Rank-Abundance Curve

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10
Q

Shannon-Wiener Index

A

H’ increases with increasing richness and evenness

H’ = - Σplnp

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11
Q

Simpson Index

A

y is the probability that any two individuals drawn from a community will be of the same species. (0 = high diversity)

y = Σp^2

D = 1 –Σn(n-1)/N/(N-1)

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12
Q

Rank-abundance curve

A

Plots proportional abundance (y) relative to abundance rank (x). Lower slope = greater evennes.

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13
Q

What are factors that influence community diversity?

A

(1) Environmental complexity
(2) Species interactions
(3) Disturbances

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14
Q

What can increase community diversity?

A

(1) Increasing environmental complexity (heterogeneity=more niches)
(2) Predation and competition (greater partitioning of resources/space)
(3) Intermediate disturbance

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15
Q

Compare community diversity with community structure

A

Community diversity = # different species in a community.

Community structure = interactions of all species in a community

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16
Q

Primary producers

A

Chemo/photoautotrophs

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17
Q

Primary consumers

A

Herbivores that eat primary producers

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18
Q

Secondary consumers

A

Carnivores that eat primary producers

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19
Q

Tertiary consumers

A

Carnivores that eat other carnivores

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20
Q

Food web

A

Diagram showing feeding relationships among organisms within an ecosystem

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21
Q

What is the relationship between the number of feeding interaction between species with the overall diversity of the community?

A

feeding interactions is INDEPENDENT of the overall diversity of the community.

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22
Q

What is the relationship between the number of trophic levels between species with the overall diversity of the community?

A

trophic levels increases with species richness. So higher community diversity is associated with increased food web complexity.

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23
Q

How are food webs and community diversity related?

A

Diversity is independent from the # of feeding interactions, but the #trophic levels (food web complexity) tends to increase with community diversity.

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24
Q

Connectedness web

A

Shows feeding relationships among organisms

25
Energy flow web
Shows connections quantified as energy flux
26
Functional web
Emphasize the influence of populations on growth rates of other populations
27
Food webs are defined in terms of...?
(1) Feeding interactions | (2) #trophic levels
28
What are indirect interactions of food webs?
(1) Indirect commensalism (2) Apparent competition (3) Trophic cascades
29
Indirect commensalism
Activities of one species indirectly benefit another species without itself being harmed or helped
30
Apparent competition
when negative impacts on species increase due to two species sharing a predator, or by one species facilitating the population growth of a predator for the other species.
31
What are the types of trophic cascades?
(1) Bottom-up | (2) Top-down
32
Keystone species
species whose interactions (usually feeding) have a disproportionately large influence on the structure of their community.
33
Altered stable state
Results from the loss of a habitat's keystone species. Altered stable state is a habitat’s shift from an established community structure to a new one.
34
What is the impact of introduced/invasive species on community structure?
Simplifies community structure complexity by eliminating trophic levels. Diversity (α) isn't decreased at the site, but diversity between sites (β) is decreased.
35
What are the energy flow constraints of energy transfer through the food web?
(1) Limited assimilation (2) Respiration (3) Heat loss
36
Assimilation (growth) efficiency
Percentage of what is initially consumed that becomes incorporated into the consumer
37
About ___% of biomass is lost when transferred from between trophic levels. The ecological efficiency is ___%.
90%; 10%
38
As trophic levels increase, biomass ___.
Decreases.
39
The most productive ecosystems have a maximum of ___ levels.
6.
40
What are the types of disturbances?
Source: Natural vs Anthropogenic Space: Small vs Large
41
What kind of species will thrive under conditions of HIGH disturbance?
Weedy, fast growing
42
What kind of species will thrive under conditions of LOW disturbance?
Competitively superior/dominant
43
What kind of species will thrive under conditions of MEDIUM disturbance?
Balance--diversity of species
44
What are the types of succession?
(1) Primary - new substrate | (2) Secondary - old substrate available
45
Primary succession
Community development on new or newly exposed geological substrate.
46
Secondary succession
Community development after a disturbance removes the community of organisms but not the soil and organics.
47
Pioneer species
Early successional species. The first species to colonize an open area after a disturbance. These species tend to be hearty plants with N2-fixing bacteria and deep roots.
48
Climax species
Late successional species. the last assemblage of species to establish themselves in a habitat. The community remains in a stable state until a disturbanceresets the system. These species tend to be slow-growing, long-lived, and highly efficient competitors.
49
How long does succession take?
Depends on (1) type and (2) composition of community
50
What are some mechanisms of succession?
(1) Facilitation (2) Inhibition (3) Tolerance
51
Facilitative succession
Pioneer species are the only ones capable of colonizing during early stages of succession. They modify their environment so that it becomes less suitable for them, but more suitable for later successional species.
52
Inhibitive succession
Earlier occupants of an area modify the environment in a way that makes it less suitable for both early and late successional species. Late successional species can only get a foothold in an area if space is opened up by the death of earlier successional species. Late successional species eventually dominant because they are long-lived and are able to resist biotic and physical stress that wipes-out earlier successional species.
53
Tolerance
all species tolerant of the conditions in a particular environment (even climax species) can be present in pioneer community. Final composition reflects the environment's selection.
54
What are the systems/patterns of disturbance?
Autogenic (stable, biotic) vs allogenic (unstable, abiotic) succession
55
Autogenic succession
Biotic elements of a community are driving succession to a stable, unchanged equilibrium
56
Allogenic succession
Abiotic elements (disturbances, weather) prevent a community from reaching equilibrium
57
Resistance
the ability of a community to maintain | structure/function in the face of disturbances,
58
Resilience
the ability of a community to bounce back | after a disturbance.
59
What happens if the underlying environment changes?
(1) Environment composition change --> phase shift, change in community composition (2) Pulse event (predator removal) --> Altered stable state

BIOL 360 - General Ecology (12 decks)

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