Ecology

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Ecology

• Ch. 3 The Biosphere

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3.1 - What is Ecology?

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

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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 about 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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Biotic and Abiotic Factors

• Biotic Factors Any living part of the
  environment with which an organism might interact
• Ex. animals, plants, mushrooms bacteria
• Abiotic Factors Any nonliving part of the
  environment
• Ex. sunlight, heat, water, soil, etc.

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Biotic and Abiotic Factors Together

• The differences between biotic and abiotic
  factors are not always clear and simple
• Many physical factors can be strongly influenced
  by the activities of organisms
• Ex. pond muck is a combination of soil
  (abiotic) and leaf mold decomposing plant
  material (biotic)

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Biotic and Abiotic Factors
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Ecological Methods

• Scientists use three basic approaches to conduct
  ecological research. They are
• Observing
• Experimenting
• Modeling

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3-2 Energy, Producers, and Consumers

• What happens if your car runs out of gas?
• What do you need before you can play in a soccer
  game or run for 5 miles?
• Living systems need a constant input of Energy.

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Primary Producers

• Autotrophs
• Organisms that use energy from the environment to
  make complex organic compounds
• Also known as producers. Why?
• Two types
• Photosynthesis - Energy from the Sun
• Chemosynthesis - Life without Light

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Primary Producers

• Primary Producers
• The first producers of energy-rich compounds that
  are later used by other organisms
• Energy from the Sun
• Capturing light energy and using it to convert
  CO2 H2O into O2 Carbohydrates
• Energy without Light
• Using chemical energy to make Carbohydrates

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Sources of Energy
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Consumers

• Heterotrophs
• Rely on other organisms for their energy and food
  supply.
• Also known as consumers
• Why?

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Consumers

• Types of Consumers
• Herbivores
• Obtain energy and nutrients by eating plant
  materials
• Carnivores
• Kill and eat other animals
• Omnivores
• Eat both plants and animals
• Scavengers
• Consume the carcasses of dead animals
• Detritivores
• Feed on dead and decaying plant and animal
  remains
• Decomposers
• Chemically break down matter

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Beyond Consumer Categories

• These simple categories often dont express the
  real complexities of nature.
• Examples
• Hyenas (carnivores) will scavenge if they get a
  chance
• Aquatic animals will eat a mixture of algae, bits
  of animal carcasses, and detritus

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3.3 Energy Flow in Ecosystems

• Energy flows through the ecosystem in one
  direction.

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Energy Flow in Ecosystems
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Food Chain

• A series of steps in which organisms transfer
  energy by eating and being eaten.

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Food Web

• A network of many feeding interactions

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Food Web
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Food Webs and Disturbance

• Relationships in Food Webs are not simple.
• Disturbances do happen and their effects can be
  dramatic.
• Example - Marine Food Web / Krill

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Antarctic Food Web
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Trophic Levels and Ecological Pyramids

• Each level 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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What is a Trophic Level?
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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 the next level
• When one organism eats another, energy is lost.
  Where does this energy go?

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Energy Pyramid
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Biomass Pyramid

• Represents all the living tissue (food) at each
  trophic level.

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Biomass Pyramid
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Pyramid of Numbers

• The number of individual organisms at each
  trophic level usually decreases as you go up the
  pyramid of numbers.

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Pyramid of Numbers
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3-4 Cycles of Matter

• Unlike the one-way flow of energy, matter is
  recycled in the biosphere.
• Where does your body get the materials, such as
  Carbon, it needs to function? __________
• Elements , chemical compounds and other forms of
  matter are passed from one organism to another
  through biogeochemical cycles.
• Bio - ______ Geo - ______ Chemical -
  ______

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Water Cycle
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Other Biogeochemical Cycles

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

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Nitrogen Cycle
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• Phosphorus Cycle - 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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Phosphorous Cycle
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Nutrient Limitation

• Primary Productivity the rate at which organic
  matter is created by a producer.
• Controlled by the availability of nutrients
• in the environment
• How can a nutrient be a limiting factor for an
  ecosystem?
• If even a single essential nutrient is in short
  supply, primary productivity will be limited

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Nutrient Limitation

• Limiting Nutrient
• the nutrient whose supply limits productivity
• Ex. - If ample sunlight and water are available,
  the primary productivity of an ecosystem may be
  limited by the availability of nutrients.

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Nutrient Limitation

• In Soil
• Growth of crop plants is limited by one or more
  nutrients that must be taken up by plants through
  their roots
• Thats why farmers use fertilizers!
• In Aquatic Ecosystems
• Sometimes receive large amounts of a limiting
  nutrient (runoff from fertilized fields)
• The result can be an Algal Bloom which can cover
  the waters surface and disrupt the ecosystem