COMMUNITY ECOLOGY

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• COMMUNITY ECOLOGY

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OBJECTIVES

• Describe types of relationships among organisms.
• Compare primary and secondary succession.

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Community Interactions

• Community a group of populations of different
  species living close enough to interact.
• Types of Interactions
• Competition,
• Predation,
• Symbiosis.

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Competition

• The competitive exclusion principle states that
  when two species compete for the same resource or
  niche, eventually the one with the slight
  reproductive advantage will eliminate the other.

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Predation

• A true predator kills and eats the other animals
  (prey).
• A parasite spends most or all of its life living
  on another organism (host) and feeding on its
  tissues.
• A herbivore is an animal that eats plants.

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Symbiosis

• Symbiosis living together several types

Mutualism both species benefit.
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Parasitism one organism benefits and the other
is harmed.
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Commensalism one organism benefits the other
is neither harmed nor benefited.
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Ecological Succession
http//www.youtube.com/watch?vV49IovRSJDs
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• Succession gradual change in the composition
  of species over time frequently following a
  disturbance.
• 1. Primary succession - succession on a new site
  by pioneer species such as lichens eventually
  larger plants replace the pioneer species.

Lichen fungus living with algae or
cyanobacteria (mutualism).
Example colonization after volcanic eruption.
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Primary succession
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• Secondary succession
• changes occurring where soil and vegetation
  already exist.

Example gradual changes after a fire.
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Secondary succession

• Climax community
• stable, mature community that undergoes little
  succession.

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Hmm

1. Does primary or secondary succession take longer?
   Why?
2. Are pioneer species r-selected or K-selected
   species?
3. How do species cause changes in the habitat that
   will result in different species composition?

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Species Diversity

• measures the number of different species in a
  community and the relative abundance of each
  species.
• Dominant species have the highest biomass (the
  sum weight of all members of a population).
• Keystone species have a strong influence on the
  survival of other species their removal results
  in dramatic changes in the makeup of species in a
  community.
• Keystone species examples sea otter, grizzly
  bear, wolf.

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• Invasive species
• http//www.youtube.com/watch?vHAY_UsGjyZk
• An introduced (non-native) species that may
  compete with native species for resources such as
  food, space, and water.
• Examples tamarisk, zebra mussels, kudzu.
• Note Most non-native species are not invasive.

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Hmm

• How do keystone species maintain balance in
  ecosystems?
• How does the introduction of a non-native species
  influence the balance of an ecosystem?

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MATH CONNECTION

• The daily caloric requirements for male versus
  female killer whales (orcas) is shown below
• Male killer whale 308,000 kcal/day
• Female killer whale 187,000 kcal/dayCalculate
  the average caloric value of a sea otter assuming
  a male orca consumes five sea otters each day to
  meet its caloric requirement. Give your answer to
  the nearest hundredth.