Download Ecology

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Ecology is the study of the
interactions between organisms
and their environment.
◦ Interdependence is a key theme
found throughout ecology.
◦ Living things depend on each
other in complex ways for
survival.
◦ Ecological models can be
used to study this complexity.
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The hierarchy of environmental
organization from largest to smallest
is: Biosphere, Ecosystems,
Communities, Populations, and
Organisms.
◦ Biosphere —thin zone of the Earth that
supports life.
◦ Ecosystem —all living and nonliving parts
of an ecosystem
 Biotic factors—living organisms
 Abiotic factors—nonliving parts.
◦ Community—all the
organisms living in a certain
area.
Example: pond community
◦ Population—all the
organisms of the same
species living in the same
area.
Example: frogs in a pond
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Two strategies exist to deal with fluctuations
in environments.
◦ Conformers—organisms who do not regulate their
internal conditions; they change with the
environment. Ex: ectothermic animals
◦ Regulators—organisms that use energy to control
some of their internal conditions.
Ex: endothermic animals
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Sometimes, adjusting isn’t possible and
organisms must temporarily escape.
Ex: Lizard hiding in the shade
Seed dormancy or animal hibernation
Migration
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Sunlight is the main source of energy in most
ecosystems
Energy flows from sunlight through
producers (make food) and consumers (eat
food)
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Photoautotrophs—
use solar energy
(photosynthesis) to
produce sugar
Chemoautotrophs—
use energy stored in
inorganic molecules
(chemosynthesis) to
produce
carbohydrates
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Consumers—get food by eating
other organisms or organic
wastes. (Heterotrophs)
Four types:
Herbivores—eat producers
Omnivores—eat producers
and consumers
Carnivores—eat other consumers
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Detritivores--feed on “wastes” (dead plants,
animal wastes, and dead animal carcasses.)
◦ A few are specifically classified as decomposers
because they cause decay and return important
nutrients to the soil.
Detritivores
Decomposing Detritivores
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Energy flow through an
ecosystem can be
illustrated using trophic
levels (shows an
organism’s position in a
sequence of energy
transfers)
1st level = producers
2nd level = herbivores
3rd and higher levels =
predators
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Consumers are also grouped into feeding or trophic
levels according to the foods they eat.
Many organisms feed at more than one level,
especially omnivores.
C1—first level consumers:
eat plants
C2—second level consumers:
eat C1 consumers
C3—third level consumers:
eat C2 consumers
A food chain is a model of the flow of energy through the
Organisms of an ecosystem.
C1
C2
C3
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Food web —many food
chains combine to form a
food web.
Gives more information.
◦ The members can be
identified by their trophic
level.
◦ Many organisms function on
more than one trophic level.
Which is a producer?
Which are C1 consumers?
Which are C2 consumers?
Which is a C3 consumer?
Which is a C4 consumer?
A complex food web from an aquatic ecosystem
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An energy pyramids --show
how the amount of energy
available decreases at each
level of the food chain.
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Many of the abiotic factors in an ecosystem
pass through cycles that allow the
substances to be used and reused.
Four important cycles of abiotic substances
include:
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Water cycle
Carbon cycle
Nitrogen cycle
Phosphorus cycle
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Water passes through both living and
nonliving parts of the environment. The
water cycle is maintained by evaporation,
transpiration, condensation and
precipitation.
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Photosynthesis and cellular respiration form the
basis of the carbon cycle.
In the past 150 years, atmospheric carbon
dioxide has risen more than 30%..mostly due to
the burning of fossil fuels
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Air is 78% nitrogen gas. Most organisms cannot use nitrogen in
this form.
Nitrogen-fixing bacteria change nitrogen gas into nitrates which
can be used by living things to make proteins and nucleic acids.
◦ Live in the soil and on the roots of certain plants (beans, peas,
clover and alfalfa).
◦ Receive carbohydrates from plants and produce nitrogen for
plants
◦ Release extra nitrogen into the soil.
Decomposers--make the nitrogen from decaying organisms and
wastes available in the soil by turning it to ammonia (NH3) which
changes in the soil to ammonium (NH4+) in a process called
ammonification.
Soil bacteria turns ammonium into nitrites (NO2-) and nitrates
(NO3-) in a process called nitrification. Plants can use the
nitrates and then animals can eat the plants.
Anaerobic bacteria return nitrogen to the air by breaking down
soil nitrates in the process of denitrification.
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Phosphorus is necessary for healthy bones, teeth, and the
formation of DNA and RNA.
The erosion of rocks is important in adding phosphorus to the
soil and water.
Excreted wastes and decaying organisms also add phosphorus
to soil and water.
Plants absorb phosphorus. Animals get phosphorus from
plants.