Notes 20 20What 20is 20Ecology by AgvP9iHG


									What is Ecology?
   Ecology is the scientific study of interactions
    among organisms and between organisms and
    their environment, or surroundings.
   The largest component of the living world is
    the biosphere. The biosphere contains the
    combined portions of the planet in which all
    of life exists, including land, water, and air or
    atmosphere. It extends about 8 kilometers
    above Earth’s atmosphere to as far as 11
    kilometers below the surface of the ocean.
         Levels of Organization
   The study of ecology ranges from the study of
    an individual organism to populations,
    communities, ecosystems, biomes and the
         Levels of Organization
   Organism – individual living thing
   Population – group of organisms of one type
    that live in the same area
   Community – populations that live together in
    a defined area
   Ecosystem – community and its nonliving
   Biosphere – part of Earth that contains all
The Flow of Energy
   Organic compounds – compounds that have
    both carbon and hydrogen atoms together
       eg. CH4, C6H12O6
   Inorganic compounds – do not contain
    carbon & hydrogen together
       eg. CO2, H2O, O2, NaCl
   The main source of energy for life on Earth is
   Some types of organisms rely on the energy
    stored in inorganic chemical compounds.
   These organisms are called autotrophs
    because they use energy from the environment
    to assemble simple inorganic compounds into
    complex organic molecules. They can also be
    called producers.
   Photosynthesis – light energy is used to power
    chemical reactions that convert CO2 and H2O
    into O2 and energy rich carbohydrates
   Chemosynthesis – use energy stored in
    chemical bonds to produce energy-rich
   Organisms that rely on other organisms for
    their energy and food supply are called
   Heterotrophs are also called consumers.
            Different Consumers
   Herbivores – eat only plants (cows, caterpillars,
   Carnivores – eat animals (snakes, dogs, owls)
   Omnivores – eat both plants and animals (humans,
    bears, monkeys)
   Detritivores – feed on plant and animal remains and
    other dead matter, called detritus (mites, earthworms,
    snails, crabs)
   Decomposers – break down organic matter to be
    recycled (bacteria, fungi)
          Feeding Relationships
   Energy flows through an ecosystem in one
    direction, from the sun or inorganic
    compounds to autotrophs (producers) and then
    to various heterotrophs (consumers)
   Food Chain - series of steps in which
    organisms transfer energy by eating and being
          Feeding Relationships
   Food Web - a network of complex interaction.
    Links all food chains in an ecosystem together
   Trophic Level – each step in food chain or
    food web. Autotrophs are 1st trophic level,
    consumers are 2nd, 3rd, or higher trophic levels
             Ecological Pyramids
   A diagram that shows the relative amounts of
    energy or matter contained within each trophic
    level in a food chain or food web.
   Three kinds of ecological pyramids:
       Energy pyramid
       Biomass pyramid
       Pyramid of numbers
              Energy Pyramid
   Only 10 percent of energy available at each
    trophic level is transferred to organisms at next
    trophic level
             Biomass Pyramid
   Total amount of living tissue within a given
    trophic level
          Pyramid of Numbers
   Numbers of individual organisms at each
    trophic level. (Forest ecosystems may have
    one tree for many insects)
   Ecological pyramids show the decreasing
    amounts of energy, living tissue, or number of
    organisms at successive feeding levels. The
    pyramid is divided into sections that represent
    each trophic level. The area of each level
    symbolizes the amount of energy or matter
    remaining at that level.
Cycles of Matter
             Cycles of Matter
   Energy flows in only one direction in an
    ecosystem. Matter is recycled within and
    between ecosystems.
   This is done through biogeochemical cycles.
   Cycles of Matter
The Water Cycle
                 The Water Cycle
   Evaporation – process by which liquid water changes to
    water vapor
   Transpiration – process by which water evaporates from
    leaves of plants
   Condensation – process by which water vapor changes to
    liquid water
   Runoff – process by which water flows over the surface of the
   Precipitation – process by which water, in any form, falls
    from the atmosphere to the Earth’s surface
   Seepage – process by which water soaks into the ground
              Nutrient Cycles
   Every living organism needs nutrients to grow
    and carry out essential life functions. Like
    water, nutrients are also recycled
The Carbon Cycle
            The Nitrogen Cycle
   Nitrogen Fixation – only certain types of
    bacteria can use nitrogen from the air. They
    live in the soil and on the roots of plants called
    legumes. They convert nitrogen gas into
    ammonia in the process of nitrogen fixation.
    Other bacteria convert the ammonia into
    nitrates and nitrites that can be used by
    producers to make proteins.
   Decomposers return nitrogen to soil as
    ammonia – producers then take it in
   Other bacteria convert nitrates into nitrogen
    gas in denitrification. Nitrogen gas then
    returns to atmosphere
The Nitrogen Cycle
What Shapes an
         Biotic and Abiotic Factors
   Ecosystems are influenced by a combination of
    biological and physical factors
       Biotic factors – include all living things with
        which an organism might interact (birds, trees,
        bacteria, mushrooms)
       Abiotic factors – physical or nonliving factors that
        shape an ecosystem (wind, nutrient availability,
        temperature, precipitation)
   Together, biotic and abiotic factors determine
    the survival and growth of an organism and the
    productivity of the ecosystem in which the
    organism lives.
   The area where an organism lives is its
            Carrying Capacity
   Carrying Capacity is the greatest number of
    individuals of a particular species that an
    environment can support. Varies depending in
    the species, the time of year and food
   Limiting factor – unfavorable factor such as
    temperature, disease, predation that prevents
    organisms from achieving their biotic potential
Limiting Factors
   Full range of physical and biological
    conditions in which an organism lives and the
    way in which the organism uses those
       No two species can occupy the same niche.
          Community Interactions
   Competition – when organisms of the same or
    different species attempt to use an ecological
    resource in the same place at the same time.
       eg. Two trees competing for sunlight, two lizard
        species competing for the same food, two members
        of same species competing for a mate
          Community Interactions
   Predation – one organism captures and feeds
    on another
       eg. Cheetah (predator) chases and kills an antelope
          Community Interactions
   Symbiosis – two species living closely together.
    Three classes: mutualism, commensalism, parasitism
       Mutualism – both species benefit (bees pollinating
        flowers, birds on rhino, termites & protozoans)
       Commensalism – one species benefits while other is
        unharmed (orchid in tree, remora on shark, barnacles on
       Parasitism – one species benefits while the other is harmed
        (tick on deer, leech on human, tapeworm in mammals)
Symbiotic Relationships Mutualism—both species benefit (top left ): The ant cares for the aphids and
protects them from predators. The aphids produce a sweet liquid that the ant drinks. Commensalism—one
species benefits; the other is neither helped nor harmed (top right): The orchid benefits from its perch in the
tree as it absorbs water and minerals from rainwater and runoff, but the tree is not affected. Parasitism—one
species benefits while the other is harmed (bottom): A flea feeds on the blood of its host, which can be
harmed by diseases the flea carries.
          Ecological Succession
   Ecosystems are constantly changing in
    response to natural and human disturbances.
    As an ecosystem changes, older inhabitants
    gradually die out and new organisms move in,
    causing further changes in the community –
    this is known as ecological succession.
   Primary succession – succession that occurs
    on surfaces where no soil exists eg. new
    islands built from volcanic eruptions, land
    covered by lava, bare rock exposed by glacier.
       First species to populate are pioneer species.
        Often lichens
   Secondary succession – changes that occur in
    an existing community without removing the
    eg. land cleared and plowed but left
    abandoned, wild fires burning woodlands

Climax community – final community which is
 stable, complex and tends to stay the same
 unless disturbed
Ecological Succession

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