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chanchan27104
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Ecology
study of interactions of organisms with their biotic and abiotic environment
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Environmentalism
social/political movement to raise concerns about environmental issues
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Population Ecology
How many individuals live in a given area
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Community Ecology
Species interactions' effects on community structure
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Ecosystem Ecology
Energy flow and chemical cycling
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Landscape Ecology
Exchanges between arrays of ecosystem
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Populations are characterized by
- dispersion
- growth
- survivorship
- age structure
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Dispersion
Distribution in space and time
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Dispersion Dependent on Two Factors
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Range
geographical area in which a species can occur
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Growth
Change in population size with time
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Growth is Dependent on
- # of individuals in population to reproduce
- capacity of organism to reproduce
- availability of required resources
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Factors affecting rate of change in population size
- reproductive capacity = r
- # of reproductive individuals = N
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G = rN
- "J-curve"
- Unlimited Growth
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Growth equation must reflect
- reproduction of a population
- Effect of carrying capacity K
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With carrying capacity, formula becomes
G = rN [(K-N)/K]
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Limiting Factor
single environmental factor that sets the carrying capacity
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When population exceeds carrying capacity, three outcomes are possible
- population size drops to original K
- excess individuals despoil environment, reducing K and population falls to new, lower K
- Environmental stress causes population to crash to or near extinction
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Survivorship Patterns
population life history patterns
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Three Basic Patterns of Survivorship
- Type I - low infant mortality
- Type II - constant mortality
- type III - high infant mortality
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Two Types of Life Cycle Strategies
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"Weedy"
- many offspring with little or no parental input in raising
- disperses widely
- Ex: weeds, oysters
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"Stable"
- fewer offspring, much parental input in raising
- disperse less widely- raised in stable environment
- Ex: whales, humans, coconut palm
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Age Structure
bar graph of # of individuals in various age classes
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Three Ecologically Relevant Age Classes
- preproductive - too young to reproduce
- reproductive - age of production
- postreproductive - too old to reproduce
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