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15 Cards in this Set
- Front
- Back
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What are the 2 overarching themes/concepts for population regulation?
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1) Abundance varies from place to place.
2) No population can grow geometrically for very long. |
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What are the 2 types of density factors in terms of population regulation?
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- Density dependent factors
- Density independent factors |
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Define:
Density dependent factors |
a) proportion of organism affected changes with population density
b) Usually Biotic factors (exa: diseases) |
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Define:
Density independent factors |
a) Same proportion of organism affected regardless of population density.
b) Usually abiotic factors (EXA: Climate, catastrophe) |
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How is the word "proportion" important in the definition of density independent/dependent factors?
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Proportion ≢ a discrete number/amount.
e.g. For a density dependent factor, 30% of the population will be affected regardless of the population *size*. |
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When (birth rates) = (death rates) ...
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...a population stops growing.
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Important Principle!
No population stops increasing unless... |
...the per. capita rate of birth or death is density-dependent.
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Populations can only be regulated by _____-_____ _____.
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density-dependent factors
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Differences in equilibrium densities can be caused by variation in...
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...density-dependent factors or density-independent factors.
i.e. from biotic or abiotic factors. |
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What are the 3 main schools of thought for Population Regulation?
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1) Climate School
2) Biotic School 3) Intrinsic School |
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What are 2 commonalities between the biotic and climate schools of thought?
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1) Reliance on intrinsic factors
2) Individuals as "marbles" |
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What are the 2 main ideas for Intrinsic Regulation?
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1) Populations may be self-regulatory
2) Regulations occur through phenotypic or genotypic changes in population. |
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What is Chitty's hypothesis?
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"All species are capable of regulating their own populatoin density without destroying the renewable resources of their environment or requiring their enemies or bad weather to keep them from doing so."
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What are 3 important things to remember about Intrinsic Regulation?
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- Not all species will evolve self-regulation
- Mechanism involves mutual interference (e.g. spacing behavior) - The most important environmental factor for intrinsically regulated population's is...other organisms of the same species. |
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Intrinsic regulation is most applicable to...
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...vertebrates.
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