Introduction to Community Ecology

• What is the largest level of ecosystem complexity?

  Biosphere
• What does the biosphere encompass?

  All life and parts of Earth supporting life
• What is an ecosystem?

  System formed by organisms and environments
• What defines a community in ecology?

  Group of organisms living together and interacting
• What is a population in ecological terms?

  Group of individuals of the same species
• What is the lowest level of ecosystem complexity?

  Individual organism
• What is ecology?

  Branch of biology studying organism relations
• What does community ecology focus on?

  Relationships of organisms living together
• What are the types of interactions in a community?

  • Intraspecific: same species interactions
  • Interspecific: different species interactions
  • Effects: Positive (+), Negative (-), Neutral (0)
• What is competition in ecological terms?

  Interaction where organisms compete for resources
• What is the competitive exclusion principle?

  Two species cannot coexist if competing for resources
• What did Gause study in Paramecium spp.?

  Effects of competition on survival
• What is an ecological niche?

  Specific role/job of an organism in an ecosystem
• What does resource partitioning achieve?

  Limits niche overlap among species
• What is character displacement?

  Divergence of traits in sympatric populations
• What is predation?

  Interaction where one species eats another
• What adaptations do predators have?

  Claws, teeth, fangs, stingers, and poison
• What adaptations do herbivores have?

  Teeth and digestive systems adapted for plants
• What are the types of symbiotic relationships?

  • Mutualism (+/+)
  • Commensalism (+/0)
  • Parasitism (+/-)
• What is the role of keystone species?

  Exert strong control on community dynamics
• What is an ecosystem engineer?

  Species that physically change ecosystems
• What is an ecological disturbance?

  Temporary change causing pronounced ecosystem change
• What are examples of natural disturbances?

  Drought, fire, tornado, volcanic eruption
• How do humans impact ecosystems?

  Reduce species diversity through disturbances
• What is primary succession?

  Succession occurring where no soil exists
• What are pioneer organisms?

  First species to colonize barren environments
• What is secondary succession?

  Succession in areas where soil remains
• What is evapotranspiration?

  Evaporation from soil plus transpiration from plants
• What are the two main climatic factors affecting biodiversity?

  Solar energy and water availability
• How does climate affect species richness?

  Species richness declines along equatorial-polar gradient
• What is the relationship between latitude and species diversity?

  Species diversity generally declines towards poles
• What is the role of solar energy in ecosystems?

  Primary source of energy for ecosystems
• What is the significance of the trophic structure?

  Describes feeding relationships and energy transfer
• What is the difference between a food chain and a food web?

  A food web consists of multiple food chains
• What is the energetic hypothesis?

  Length of food chains limited by energy transfer inefficiency
• What is the dynamic stability hypothesis?

  Long food chains are less stable due to fluctuations
• What is the design constraint hypothesis?

  Predators should be larger than their prey
• What defines a dominant species?

  Most abundant or highest biomass species
• What is a keystone species?

  Species that exert strong control on community structure
• What is the role of ecological disturbances?

  Cause pronounced changes in ecosystems