Populations interact in communities

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Populations interact in communities
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3 types of interactions between species

• Competition (for a scarce resource)
• -food, water

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• --hidey holes or nest sites

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• --sunlight

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Competitive exclusion

• If two species are too similar in what they eat,
  when they eat it, where they live, etc. then one
  species may drive the other to extinction in that
  location.

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Niche

• Not only where an organism lives (habitat) but
  what it does
• -what it eats
• -when its active
• -what other organisms eat it
• -how it alters the environment its in
• Analogy Habitat is an organisms address
• Niche is its job

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Example

• Oak tree
• Habitat deciduous forest
• Niche
• absorb sunlight by photosynthesis
• absorb water and mineral salts from the soil
• provide shelter for many animals and other
  plants
• act as a support for creeping plants
• serve as a source of food for animals
• cover the ground with their dead leaves in the
  fall.
• If you eliminate oak trees, their job does not
  get doneor something else has to do it.

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Ecology principle No two species can occupy the
same niche

• Resource partitioning (dividing) Differences in
  how or when a resource is used can allow two
  species to coexist.
• brown anole near the ground
• green anole is restricted to the canopies of
  trees
• the resource (space, insects) has been
  partitioned among the two species

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2. Predator-prey interactions

• Herbivores vs. plants
• Carnivores vs. herbivores

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Adaptations

• Inherited characteristics that help an organism
  survive and reproduce

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For predators

• Camouflage

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• Sharp senses

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• Weapons

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• Behavior

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Prey adaptations

• Camouflage

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• Armor

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• Mimicry

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• Behavior

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3. Symbiosis

• Sym / biosis
• Together / live
• A close long-term relationship of two dissimilar
  species

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1. Parasitism

• One organism benefits and the other is harmed

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2. Commensalism

• One species benefits and the other is neither
  harmed nor helped

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3. Mutualism

• Both species benefit