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					13.6 Pyramid Models
  KEY CONCEPT
    Pyramids model the distribution of energy and matter
    in an ecosystem.
13.6 Pyramid Models
  An energy pyramid shows the distribution of energy
  among trophic levels.
  • Energy pyramids compare energy used by producers
    and other organisms on trophic levels.
  • Between each tier of an energy
    pyramid, up to 90 percent of the
    energy is lost into the
    atmosphere as heat.
  • Only 10 percent of the energy at
    each tier is transferred from one
    trophic level to the next.
                       energy
                                   energy transferred
                        lost
13.6 Pyramid Models
  Other pyramid models illustrate an ecosystem’s biomass
  and distribution of organisms.
  • Biomass is a measure of the total dry mass of organisms in
    a given area.

             tertiary                       75 g/m2
             consumers



                                            150g/m2
             secondary
             consumers


             primary
             consumers                      675g/m2




             producers
             producers                    2000g/m2
13.6 Pyramid Models

  • A pyramid of numbers shows the numbers of individual
    organisms at each trophic level in an ecosystem.

             tertiary                                 5
             consumers


              secondary                         5000
              consumers


              primary                        500,000
              consumers




               producers
               producers                  5,000,000




  • A vast number of producers are required to support even a
    few top level consumers.
13.6 Pyramid Models

  Create your own pyramid model
  • Draw an energy pyramid for the desert food chain below.
  • Use arrows to illustrate the flow of energy.
13.6 Pyramid Models
13.6 Pyramid Models

   Written portion:

• +3 = define and give accurate example
   o +1 = adapted to own environment
   o +1 = divergent evolution
                                                Needed 3 of
   o +1 = NO gene flow                          these
   o +1 = REPRODUCTIVE ISOLATION
   o +1 = cannot produce fertile offspring
• +2 = Mention speciation and tell what it is

				
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posted:5/29/2012
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