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31 Cards in this Set
- Front
- Back
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The 2 general models for communites are:
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1) The Equilibrium Model
2) The Non-Equilibrium Model |
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What are 4 characteristics of:
The Equilibrium Model? |
1) Organized by biotic interactions (predation and competition)
2) Focused on stability 3) Classic model (for ~60 years) 4) Good fit for organization of some communities |
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What are 2 characteristics of:
The Non-Equilibrium Model |
1) Focus is on the small spatial scale
2) Emphasizes *patches* and *disturbance* |
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Define:
Patch (in terms of the non-equilibrium model) |
A discrete area of *any* size.
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Define:
Local patch (in terms of the non-equilibrium model) |
Covers a few square meters to a few hectares.
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What are 5 characteristics of:
Disturbance (in terms of the non-equilibrium model) |
1) A discrete event
2) Disrupts community structure 3) Changes available resources, substrate availability, or the physical environment 4) Differ in intensity and frequency 5) Effect on community dynamics and composition |
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What are the 2 categories of disturbance?
Define them briefly, and give examples for each category. |
Exogenous Disturbance: Disturbance arises from *outside* the community.
e.g. fires, floods, winds Endogenous Disturbance: Disturbance arises from *inside* the community. e.g. predation, disease outbreaks |
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Define:
Non-Equilibrium Community |
One in which the time it takes to recover *exceeds* frequency of the disturbance.
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How can the impacts of disturbance be further magnified in a community?
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Impacts of disturbance can be magnified in communities that are already stressed by human activities.
(e.g. pollution, climate change) |
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Describe the graphs in FIG [21.1] (pg. 427) in terms of disturbance and recovery.
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...okay.
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A Case Study: Coral Reefs
What are 3 points about the history of coral reefs? |
1) They've been around for 60 million years.
2) There is great biodiversity on reefs 3) They've been stable for the past 200,000 years. |
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A Case Study: Coral Reefs
How has our view of coral reefs changed recently in terms of their stability. |
On a *geologic* time scale, reefs have been stable for 200,000 years.
On a *ecologic* time scale: 1) Reefs are regularly disturbed by tropical storms 2) Recovery time for reefs is in decades. |
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A Case Study: Coral Reefs
What does FIG [21.3] (pg. 429) say about how tropical storms affect the coral on reefs? |
Violent storms will remove coral from the reefs.
Exposed corals are removed more than protected corals. (e.g. the storm in 1972 removed *all* coral from the Exposed Crest) |
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A Case Study: Coral Reefs
What does FIG [21.4] (pg. 429) say about larval recruitment rates on coral reefs? |
1) Larval recruitment is variable.
2) Recruitment is dependent on available space (i.e. larvae cannot attach to other living coral) 3) There were generally no "good" or "bad" recruitment years (no pattern) |
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A Case Study: Coral Reefs
What kind of of non-natural disturbance threatens coral reefs currently? |
Coral Bleaching
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A Case Study: Coral Reefs
Describe the process of Coral Bleaching. (4 points) |
1) Zooxanthella - a symbiotic algae.
2) Algae gives coral it's color and helps in growth. 3) Coral is sensitive to water temperature changes. 4) When water temperature increases, the coral expel the algae, resulting in *bleaching*. FIG [21.5] (pg. 430) |
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Island Communities:
What important discovery did Alexander Von Humboldt make in 1807? What islands can this discovery be seen most easily in? |
Large islands...have more species than small islands!
The Galapagos Islands [21.19] (pg. 440) |
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The relationship between species and area can be described by a simple equation called the:
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Species-Area Curve
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Give the 2 forms of the equation for a Species-Area Curve, and define each of the variables.
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S = cA^z
OR log(S) = log(c) + z[log(A)] Variables: S = # of species c = A constant: (# species) / (unit area) A = Area of island z = A constant: slope of S vs. A |
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Species-Area Curve:
Curves with a z value of _____ fit many data sets. |
0.3
(z = ~0.3) |
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Species-Area Curve:
Define the variable "S" |
S = cA^z
OR log(S) = log(c) + z[log(A)] S = # of species NUMBER OF SPECIES |
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Species-Area Curve:
Define the variable "c" |
S = cA^z
OR log(S) = log(c) + z[log(A)] c = A constant: (# of species) / unit area The number of species per unit area. |
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Species-Area Curve:
Define the variable "A" |
S = cA^z
OR log(S) = log(c) + z[log(A)] A = Area of the island |
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Species-Area Curve:
Define the variable "z" |
S = cA^z
OR log(S) = log(c) + z[log(A)] z = A constant: Slope of S vs. A. A slope based on: the number of species as a function of the area of the island. (i.e. how the number of species varies with the size of the island) |
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Theory of Island Biogeography:
What is the "basic premise" behind the theory of island biogeography? |
For any island (or patch), S should be a balance between immigration rate and extinction rate.
*S = the equilibrium number of species |
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Theory of Island Biogeography:
Which two people came up with the above theory? When did they do this? |
MacArthur and Wilson (1967)
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Theory of Island Biogeography:
What are the 4 main characteristics for a *single island* scenario? |
1) Rates are species gained/lost per unit time.
2) Immigration rates fall as the island fills up. 3) Extinction rates increase as the island fills up. 4) Equilibrium point is where the functions cross. FIG [21.21] (pg. 442) |
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Theory of Island Biogeography:
Draw the graph in FIG [21.21] (pg. 442) Label each of the lines, the axis', and the 3 variables present. |
...okay.
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Theory of Island Biogeography:
Describe FIG [21.22] (pg. 443) How does an islands distance from the mainland affect the immigration rate? |
FIG [21.22] (pg. 443)
An increase in distance (near to far) *lowers* the immigration curve. A decrease in distance (far to near) *raises* the immigration curve. (i.e. the close an island is to the mainland, the greater immigration it will experience. Thus the curve will raise with the closer an island is to the mainland) |
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Theory of Island Biogeography:
Describe FIG [21.22] (pg. 443) How does island size affect the extinction rate? |
FIG [21.22] (pg. 443)
An increase in island size (small to large) *lowers* the extinction curve. A decrease in island size (large to small) *raises* the extinction curve. (i.e. a smaller island experiences a greater rate of extinctions.) |
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Theory of Island Biogeography:
What other types of "islands" might this theory be applicable to? |
Habitats in terrestrial areas that are secluded can be considered a type of "island".
e.g. mountain tops |
