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community - species found at a certain area

  • individualistic concept - community nothing more than collection of organisms that happen to live in same place
  • holistic concept - community acts as integrated unit (superorganism)
  • ecotones - area where environment suddenly changes

niche - role an organism plays in the ecosystem

  • interspecific competition - when not enough resource for 2 organisms
    • interference competition - fighting over resources
    • exploitative competition - consuming shared resources
  • fundamental niche - entire niche that organism can use
  • realized niche - actual niche that organism occupies
  • competitive exclusion - no 2 organisms can occupy same niche if resources limited
    • species that can use resource more efficiently will prevail
    • can subdivide niche to avoid direct competition
    • grow more similar >> more likely to compete
  • sympatric species - avoid competition by living in different parts of habitat or using different resources
  • character displacement - natural selection makes competing organisms different

coevolution between predator/prey - populations oscillate since predator depends on prey

  • lag and offset oscillations between predator/prey
  • keystone species - presence has much influence on the community
    • ex. beavers

predation - consuming of 1 organism by another

  • kill predator >> increase prey population
  • coevolution >> predator/prey continually develop better offense/defense
  • plant defenses - mostly uses morphological defenses (thorns, spines, hairs)
    • secondary chemical compounds - toxic or disturbs metabolism
  • animal defenses - tries to show predators that they taste bad
    • chemical defenses - used as weapons against predator
    • warning coloration - tells predators that they have toxic chemicals
    • cryptic coloration - blends in w/ surroundings
  • reduces competition
  • indirect effects - 1 organism affecting another indirectly through a 3rd organism
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