Download Ecology

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Ecology and Biosphere
*Study of the interactions of
organisms with each other and
their environment
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*Biotic-living
*Abiotic- non-living
Biotic
Biotic
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Abiotic
Abiotic
* Population-group of organisms of same species in a
specific area
* Community- all the populations in an area
* Ecosystem- community + abiotic factors
* Biome- Major ecosystem that occupies a broad
geographic region influenced by climate and
characterized by dominant vegetation
* Biosphere- all portions of Earth inhabited by life /
all of Earth’s ecosystems
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*Determined by…
*sunlight,
*temperature,
*water,
*wind,
*elevation
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A.
Interactions
1.
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Competition—usually for resources
Niche—organism’s role in its environment
~Can’t have 2 species with the same niche in the
same area because of the Competitive Exclusion
Principle—2 extremely similar species cannot co-exist
in the same place because one will be slightly better
at getting the resources and reproduce more.
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Resource Partitioning—resources are divided so
that species can co-exist and each have it’s own
niche
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2. Predation
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Animalanimal = predator / prey
Animalplant = herbivory
3. Symbiosis
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Mutualism (+,+)
Parasitism (+,-)
Commensalism (+, 0)
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B. Trophic Structures
* Food web—Messy = Stable
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2.
Length of Food Chain in Food Web
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Energetic Hypothesis—food chain can’t be long
because there is an insufficient transfer of energy
(10% Rule)
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Dynamic Stability—shorter chains are more stable
because disruptions are magnified as you go up
(the lower you wipe something out, the more
effect it has)
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C.
Community Stability
1.
Dominant Species—highest in terms of biomass
(usually a plant)
2.
Keystone Species—not most abundant but most
important due to ecological role. If it’s removed
from ecosystem there’s a major effect
3.
Succession—Predictable sequence of communities
that follow each other after a disturbance
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* Succession Terms
* Disturbance—what originally “damages” ecosystem
* Primary Succession—start with a virtually lifeless area
* Secondary Succession—start with some biomass left
* Pioneer Species—first species to come into an area
* Climax Community—end stage / stable / due to climate
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A. Density: # of organisms/area
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Quantitative
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2 lions per mile2
Qualitative
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The density of lions in my backyard is sparse.
B. Distribution: How organisms are arranged/placed
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Determined by resources and social behavior
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C. Survivorship: See reading
D. Life histories: See reading
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D. Population Growth
* Variables:
dY = amount of change
dt = change in time
B = number of births
D = number of deaths
N = population size
K = carrying capacity
rmax = maximum per
capita growth rate of
population
b = per capita birth rate
m = per capita death rate
Population Growth:
dN = B – D OR dN = bN - mN
dt
dt
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Density Dependent Factors:
Population limiting factors whose effect
depends on population density
Density Independent Factors:
Population limiting factors that are not
dependent on population density
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A.
Productivity—turning light into sugars
1.
Gross Primary Productivity (GPP)—amount of
light energy converted to chemical energy in
photosynthesis over time
2.
Net Primary Productivity—
(amount of GPP) – (energy used by plant in
cellular respiration [R])
NPP = GPP – R
3.
Limits on Production—sun (intensity, depth,
penetration); limits on photosynthesis (water);
limiting nutrients (N & P)
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Net Annual Primary Production vs. Mean
Annual Precipitation
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B.
Ecological Pyramids (See Pictures)
1.
Production / Energy—amount of energy stored
at each level
2.
Biomass—amount of biological mass at each
level
3.
Numbers—number of organisms at each level
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Biomagnification—retained substances become
more concentrated as you go up the trophic
levels
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C. Greenhouse Effect—Carbon Dioxide (and other
gases) allow light through but trap the heat it
generates in the atmosphere
Global Warming—due to increased carbon
dioxide levels, causing increased greenhouse
effect
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