Transcript ECOLOGY

Ch. 18- Ecology
- The Biosphere
What is Ecology?
• It is the scientific study of
interaction among organisms and
between organisms and their
Interdependence is the Key
• Ecology:
– Greek oikos – house
– Logos –study of
What is the Biosphere?
• The biosphere is the combined
portions of the entire planet where
life exists.
Levels of Organization
• To understand relationships within the
biosphere ecologists ask questions abut
events and organisms that range in
complexity from a single individual to the
entire biosphere
Levels, cont.
• Species: a group of organisms so similar
to one another that they can breed and
produce fertile offspring.
• Populations: a group of individuals that
belong to the same species and live in the
same area.
• Communities: different populations that
live together in a defined area.
Levels, cont.
• Ecosystems: all the organisms that live in
a particular place, together with their
nonliving or physical environment.
• Biomes: a group of ecosystems that have
the same climate and dominant
Levels of Organization
Ecological Methods
• Observing
• Experimenting
• Modeling
Observing can be as simple as asking
ecological questions or be more complex
and form the first step in designing
experiments and models.
• Experimenting is used to test hypotheses.
This can be done n an artificial setting like
a lab or within natural ecosystems.
• Modeling is used to gain insight into larger,
more complex processes, such as global
warming. Models are used to make
predictions which may be tested by
observations and experiments.
• Describe the ecological method shown in
each picture that follows.
Ecosystem Components
• Biotic
– All living things that
affect the organism
• Abiotic
Oxygen concentration
Amount of sunlight
Availability of Nitrogen
Organisms in a Changing
• Each organism is able to survive within a
limited range of environmental conditions.
• A graph of performance versus values of
an environmental variable such as
temperature is called tolerance curve
Tolerance Curve
• Some organisms can adjust their tolerance
to abiotic factors such as temperature, or
• This is NOT an adaptation. It occurs
within the lifetime of the individuals. It is
not a genetic change.
Control of Internal Conditions
• Conformers
– Don’t regulate their
internal condition
– Change with the
– Internal conditions
only remain optimal IF
environment is optimal
• Regulators
– Use energy to control
their internal
– Internal conditions
remain optimal over a
range of
Niche: the job
• Generalists
– Species with broad
niches can tolerate a
range of conditions
and use a variety of
– Ex. Virginia opossum
• Specialists
– Species with a narrow
– Ex. Koalas only eats
eucalyptus leaves.
Energy Flow in the Ecosystem
• Living systems need a constant
input of energy.
• Main source of energy for life on
earth is??
• Some types of organism rely on
the energy stored in inorganic
chemical compounds.
Energy Flow, cont.
• Autotrophs
– Organisms that use
energy from the
environment to make
complex organic
– Also known as
– Two types
• Photosynthesis
• Chemosynthesis
• Heterotrophs
– Rely on other
organisms for their
energy and food
– Also known as
• Types:
Feeding Relationships
• Energy flows through the
ecosystem in one direction.
Food Chain
Food Web
What is a trophic level?
• Each step in a food
chain or food web is a
trophic level.
• Each trophic level
depends on the level
below it for energy
Ecological Pyramids
• Can be used to represent energy, matter
or number of individuals at each trophic
• Energy Pyramid: only 10% of the energy
available at one trophic level makes it to
• Biomass Pyramid: represents all the living
tissue (food) at each trophic level.
• Pyramid of Numbers: the number of
individual organisms at each trophic level
usually decrease as you go up the
pyramid of numbers.
Cycles of Matter
• Unlike the one-way flow of energy, matter
is recycled in the biosphere.
• Elements , chemical compounds and other
forms of matter are passed from one
organism to another through
biogeochemical cycles.
Water cycle
Other Biogeochemical Cycles
• Carbon - carbon is especially important
because it is the key ingredient in all living
organisms. Carbon is found in oceans,
the air, and certain types of rock
• Nitrogen - All organisms require nitrogen
to make amino acids which are used to
build proteins.
• Phosporus - Unlike carbon nitrogen and
oxygen, phosphorous does not enter the
air, it remains mostly in rock, soil minerals,
and ocean sediments. Phosphorous is of
great biological importance for molecules
like DNA and RNA.
• Primary Productivity: the rate at which
organic matter is created by a producer.
– Controlled by the availability of nutrients in the
– Limiting nutrient: the one nutrient that when
in short supply, will limit the primary
productivity of the ecosystem.