NOTES ECOLOGY

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NOTES ECOLOGY

• SPECIES INTERACTION
• COMMUNITY DISTURBANCE

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I. Populations in Communities INTERACT

• Competition struggle for resources between
  living things
• 1. Example
• a. Interspecific competition
  competition
• between species that depend on
  the
• same limited resource
• 2. Competitive exclusion is when 2
  species are
• so similar in their requirements
  that the same
• resource limits both populations
  growth. One
• species may succeed OVER the other
  one and
• take away all the resource.

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• Niche unique living arrangement of an organism
  defined by its habitat, food sources, time of day
  it is most active, and other factors
• a. Example 2 similar lizards, one eats
• on tall shrubs, other low shrubs, if
  niches
• are similar, may see competitive
  exclusion

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B. Predation

• One organism eats another
• Predator --gt the hunter
• a. Fast and strong
• b. Good senses- hearing, sight, smell
• c. Camouflage
• d. Sharp teeth, claws

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• The Prey --gt the food
• a. Good eyesight,
• hearing, smell
• b. Camouflage
• c. Fast, agile, some are
• poisonous or has
• spikes

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• Symbiotic Relationships
• 1. A close interaction between species in
  which
• one of the species lives in or on the
  other
• 2. Parasitism - one organism
  benefits
• (parasite) the other is harmed (host)
• a. Intestinal worms and animals
• 3. Mutualism both organisms
  benefit from
• each other
• a. E.coli and people tube worms and
  
• bacteria
• 4. Commensalism 0 Only one organism
  benefits while the other is NOT harmed, or
  helped- rare
• a. Spider crab using seaweed to cover
  itself to
• hide from danger

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II. Disturbances are Common in Communities

• Disturbances to communities
• 1. Fires, volcanoes, floods, storms,
  droughts
• 2. Effects can be positive
• i. Shipwreck- can be new habitat

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ii. Forest fires- some plants sprout
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• Ecological Succession
• Primary succession process by which a community
  arises in a virtually lifeless area with no soil
• ex bare rock, start from scratch
• i. bacteria, lichens --gt moss --gt pioneer
  organism
• ii. Grasses --gt shrubs --gt trees

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• Secondary succession when disturbance damages
  existing community but leaves the soil in tact
• Ex. When a farmer ploughs down
• field to dirt, then abandons it

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CLIMAX COMMUNITY When an ecosystem has reached a
stage where it doesnt change very much and the
community is fairly stable. This is the final
step in Ecological Succession, although many
communities never make it to this step before
another disturbance comes to start the process
over.
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Human Activity and Species Diversity Human
Disturbances can have a negative or positive
effect on the community-- in most cases it is
negative. Examples are Clearing of land-- this
can be done by making farms, clear cutting for
lumber, building roads, buildings or parking
lots. Introduced species-- Species that are moved
into an area that they do not normally grow
either intentionally or unintentionally. Some of
these species do not make it in their new
environment but others take over the native
(indigenous) species and strip the native species
of their resources.