Ch. 18- Ecology

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Ch. 18- Ecology

• - The Biosphere

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What is Ecology?

• It is the scientific study of interaction among
  organisms and between organisms and their
  environment

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Interdependence is the Key

• Ecology
• Greek oikos house
• Logos study of

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What is the Biosphere?

• The biosphere is the combined portions of the
  entire planet where life exists.

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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

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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.

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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 communities.

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Levels of Organization
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Ecological Methods

• Observing
• Experimenting
• Modeling

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• Observing can be as simple as asking ecological
  questions or be more complex and form the first
  step in designing experiments and models.

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• Experimenting is used to test hypotheses. This
  can be done n an artificial setting like a lab or
  within natural ecosystems.

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• 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.

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Ecosystem Components

• Biotic
• All living things that affect the organism

• Abiotic
• Temperature
• Humidity
• pH
• Salinity
• Oxygen concentration
• Amount of sunlight
• Availability of Nitrogen
• precipitation

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Organisms in a Changing Environment

• 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

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Tolerance Curve
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Acclimation

• Some organisms can adjust their tolerance to
  abiotic factors such as temperature, or pH.
• This is NOT an adaptation. It occurs within the
  lifetime of the individuals. It is not a genetic
  change.

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Control of Internal Conditions

• Conformers
• Dont regulate their internal condition
• Change with the environment
• Internal conditions only remain optimal IF
  environment is optimal

• Regulators
• Use energy to control their internal conditions.
• Internal conditions remain optimal over a range
  of environmental conditions.

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Niche the job

• Generalists
• Species with broad niches can tolerate a range of
  conditions and use a variety of resources.
• Ex. Virginia opossum

• Specialists
• Species with a narrow niche
• Ex. Koalas only eats eucalyptus leaves.

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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.

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Energy Flow, cont.

• Autotrophs
• Organisms that use energy from the environment to
  make complex organic compounds
• Also known as producers
• Two types
• Photosynthesis
• Chemosynthesis

• Heterotrophs
• Rely on other organisms for their energy and food
  supply.
• Also known as consumers
• Types
• Herbivores
• Carnivores
• Detritivores
• Decomposers.

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Feeding Relationships

• Energy flows through the ecosystem in one
  direction.

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Food Chain
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Food Web
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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

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Ecological Pyramids

• Can be used to represent energy, matter or number
  of individuals at each trophic level

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• Energy Pyramid only 10 of the energy available
  at one trophic level makes it to another.

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• Biomass Pyramid represents all the living
  tissue (food) at each trophic level.

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• Pyramid of Numbers the number of individual
  organisms at each trophic level usually decrease
  as you go up the pyramid of numbers.

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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.

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Water cycle
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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

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• Nitrogen - All organisms require nitrogen to make
  amino acids which are used to build proteins.

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• 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.

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Productivity

• Primary Productivity the rate at which organic
  matter is created by a producer.
• Controlled by the availability of nutrients in
  the environment
• Limiting nutrient the one nutrient that when in
  short supply, will limit the primary productivity
  of the ecosystem.