Intro to Ecology

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Intro to Ecology

• Chapter 18

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Interdependence A Key Theme in Ecology

• Ecology- study of the interactions of living
  organisms w/ one another and w/ their physical
  environment (soil, water,weather)
• Interdependence 1 change can affect all species
  in an ecosystem

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Ecological models help to explain the environment
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• Ecologists recognize a hierarchy of organization
  in the environment

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• A) Biosphere broadest, most inclusive, thin
  layer around Earth where life exists
• B) Ecosystems
  all organisms and
• the nonliving
  environment

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• C. Community interacting organisms living in an
  area
• D. Population all the members of species that
  live in one place _at_ one time
• E. Individual
• organisms of a
• single species

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18.2 Ecology of Orgs

• Habitat place where an organism lives
• Biotic factors living things that affect the
  organism
• Abiotic factors nonliving things (climate,
  sunlight, pH)

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The Influence of the Physical Environment
AWhat Causes Climate? 1Ecosystem distribution
results from the interaction of physical
features (soil, lakes, mountains, valleys,
oceans) with 2 key factors,
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2 FACTORS, aThe amount of solar energy
reaching different parts of Earth and seasonal
variations in that energy.
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bGlobal pattern of atmospheric and oceanic
circulation created by unequal global
distribution of solar energy.
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2The great diversity of ecosystems is partly due
to variations in climate. However, the Earths
rotation on its axis and its revolution around
the Sun are also important in determining
climate.
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BSolar Heating Drives Atmospheric
Circulation 1Hot air rises (near the equator).
When it cools, it loses moisture (heavy rains
in the tropics).
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2There are areas of low pressure when rising air
cools, drops its moisture, and moves toward the
poles, then it dries, falls, picks up moisture,
reheats,
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CWhy It Rains Where It Does 1Latitudes aAt
30o north and south the air is dry because it
lost almost all moisture in the tropics.
Most of the Earths great deserts occur near
30o north and south latitude.
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bAt 60o north latitude, the air is rising and
cooling and losing moisture and the great
temperate forests occur as a result.
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2Rain-shadow Effect Mountains force
approaching air up, cooling it, and causing
precipitation on the wind- ward side. Areas on
the leeward side are dryer. Vegetation varies
with rainfall.
(windward)
(leeward)
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Organisms in a Changing Environment

• Acclimation organisms can adjust their
  tolerance to abiotic factors
• Control of Internal Conditions
• Conformers organisms that do not regulate their
  internal conditions, change w/ environment
• Regulators use E to control their internal
  conditions

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• Escape from Unsuitable Conditions
• Some species survive by becoming dormant or by
  migrating
• Dormancy state of reduced activity
• Ex- drought
• Migration seasonal movement
• Ex- birds

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• Niche way of life, or role in an ecosystem
• Earthworm
• Niche

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18.3 E Transfer

• Producers (autotrophs) photosynthetic, make
  carbs by using E from sun

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• Measuring Productivity
• Gross primary productivity rate _at_ which
  producers capture E by producing organic
  compounds
• Net primary productivity rate at which biomass
  accumulates
• biomass dry weight of tissue and other
  organic matter

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• Consumers obtain E by eating other organisms or
  organic molecules from organisms (herbivores,
  omnivores, carnivores, detritivores, decomposers)

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Detritivores- organisms that obtain E from
organic waste and dead bodies at all trophic
levels Ex- vulture and worms Decomposers-
cause decay, release nutrients back into
the environment (recycle) Ex fungi and
bacteria
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Food Chain single pathway of E transfer
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• Food web network showing all paths of E
  transfer

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-1st Trophic Levelproducers (a)use sunlight to
make food (b)absorb nitrogen and minerals
Ex--algae
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-2nd Trophic Levelherbivores (a)animals that
eat plants (b)primary or 1st order consumers
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(c)Excows, horses, caterpillars,etc. (d)Must
be able to breakdown cellulose of plant cell
walls.
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-3rd Trophic Levelcarnivores (a) animals that
eat herbivores (b) 2nd order consumers (c)
Extigers, wolves, snakes (d) This level also
contains the omnivores that
eat both plants and animals (bears
and humans).
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-4th Trophic Levelcarnivores (a)tertiary
consumers (top carnivores) (b)Carnivores
that eat carnivores. (c)3rd order
consumers (d)Exhawk eats a snake
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Feeding Trophic Consumer
Type Level Level Top
carnivore 4th 3rd Carnivore
3rd 2nd Herbivore 2nd 1st Producer
1st
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- about 10 of E available at one trophic level
is transferred to the next trophic level
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Energy Pyramids
90 of available E is lost at each level.
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• E Transfers Btwn Trophic Levels Are Inefficient
• Large amts of E are released
• and lost as HEAT in each E
• transfer

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E Loss Limits the of Trophic Levels in an
Ecosystem - Most terrestrial ecosystems only
involve 3-4 trophic levels -Too much E is lost _at_
each level to allow more
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18.4 Ecosystem Recycling Materials Cycle
Between Organisms and Nonliving Environment
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• A) Water cycle evaporation, transpiration, and
  precipitation

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• Water cycles in 2 ways
• (a) Nonliving
• Sun heats up surface water it evaporates
• Water vapor condenses in the atmosphere and
  falls to Earth as precipitation
• large part of it seeps into the soil and
  becomes groundwater

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• (b) Living
• Water is absorbed by plant roots and enters
  the plant
• Transpiration occurs from leaves

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1Water, compared to all of the other nonliving
components in ecosystems, has the greatest
influence on an ecosystems inhabitants. 2Its
availability often determines the diversity of
the ecosystem.
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• B) Carbon Cycle C is returned to environment in
  4 ways
• CO2 in the atmosphere and H2O is used in
  photosynthesis to build organic molecules
• CO2 and water are products of cellular
  respiration

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• 3) Decomposers release CO2 into the atmosphere
  when they break down dead organisms
• 4) Combustion- CO2 is released when plant
  material is burned
• Ex plant material
  (wood), fossil fuels
  (coal, oil, gas)

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C) Nitrogen Cycle
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1) Atmospheric N (N2) is very difficult to
remove and use directly - most organisms are
incapable of doing so
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2) N fixation converting N2 to nitrate 3)
Bacteria in soil or root nodules of legumes are
the only organisms that
can do this
(nitrogen-fixing bacteria)
(Nitrogen-fixing Cyanobacteria)
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• 4) N Cycle 4 stages
• (a) Assimilation absorption and
• incorporation of N into plants and
• animals
• (b) Ammonification production of
• ammonia by bacteria during the decay
• of N containing organic matter.
• many animals excrete N in urine dung then
  another type of bacteria turns it back into
  ammonia.

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• (c) Nitrification production of nitrate
• (NO3-) from ammonia
• (d) Denitrification conversion of
• nitrate to N2.
• growth of plants is often limited by the
  availability of nitrate and ammonia in the soil.
  

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• D) Phosphorus Cycle
• 1) P in rocks and soil contain calcium phosphate
  and when it is dissolved in water it becomes
  phosphate ions (PO4-)
• 2) Absorbed in plants, it is used to
• build organic molecules (DNA
• ATP)
• Animals eat plants and reuse P

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• 3) When plants and animals die, bacteria change P
  back to phosphate ions
• P added to lakes from detergents and fertilizers
  can cause photosynthetic algae to grow rapidly
  (algal bloom)
• When algae die, bacteria feed on it, and use the
  dissolved O2.
• Animals living in the lakes will suffocate