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