XVI' Community Ecology

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XVI. Community Ecology

• A. Niche
• B. Competitive Exclusion
• C. Predator-Prey Relationships
• D. Mimicry
• E. Symbiotic Relationships

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A. Niche

• 1. How organisms utilize their environment
• 2. Niche is a pattern of living, while habitat is
  a place
• 3. Fundamental niche- niche a species is capable
  of occupying utilizing
• 4. Realized niche- niche the species actually
  occupies uses

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B. Competitive Exclusion

• 1. If resources are limited, no two species can
  occupy use the same niche indefinitely
• 2. Competition drives one species to extinction
• 3. Partitioning the niche avoids competition
• 4. Partitioned by different areas of habitat,
  different food sources, /or different times

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C. Predator-Prey Relationships

• 1. Predators control prey populations prey
  control predator populations
• 2. Predator-prey interaction provides strong
  selective pressure on both populations
• 3. Predators prey coevolve
• 4. Mesozoic fish could crush eat molluscs,
  molluscs evolved thicker shells with defensive
  spines

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D. Mimicry

• 1. Batesian
• 2. Mullerian

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1. Batesian Mimicry

• a. Harmless species resembles dangerous or
  unpleasant species
• b. Monarch viceroy butterflies
• c. Coral snake Scarlet Kingsnake if nose is
  black, jump back Jack if nose is red, nothing to
  dread

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2. Mullerian Mimicry

• Two or more unrelated but protected species
  resemble one another
• b. Bees wasps

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E. Symbiotic Relationships

• 1. Two or more species living together in
  specific relationships
• 2. At least one benefits
• 3. Tend to coevolve
• 4. Commensalism
• 5. Mutualism
• 6. Parasitism

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4. Commensalism

• a. One species benefits, the other neither
  benefits nor is harmed
• b. Barnacles whales humans intestinal
  bacteria
• c. Often hard to rule out if host is helped or
  harmed

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5. Mutualism

• a. Cooperation between species mutually benefits
  both
• b. Coevolution of angiosperms insects some
  plants have one specific pollinator
• c. Ants acacia

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6. Parasitism

• a. One organism serves as a host to another
  organism
• b. Host is harmed, but not killed
• c. Parasite is much smaller than host
• d. External- lice, fleas
• e. Internal- tapeworms, flukes

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