Download Keystone Species

Activity #17:
Habitats
EQ
• What are some of the roles of the organisms in
ecosystems?
• Why do you find similar groups of organisms in
similar environments around the Earth?
• What factors affect population size and how does
the size of a population size affect its environment?
Challenge Question
• Describe a habitat.
Vocabulary
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Niche
Tolerance
Habitat
Commensalism
Competitive Exclusion Principle
Keystone Species
Mutualism
Predation
Symbiosis
Tolerance
• Ability to survive and reproduce under a variety of
environmental circumstances
• Outside the optimum range causes stress
• Struggling to maintain homeostasis
• For any environmental factor, going beyond the
upper or lower limit can lead to death
Habitat
• General place where an organism
lives
• Organisms will live where they can
tolerate (or handle) the conditions
Niche
• What an organism does in its habitat, how it
interacts with its environment, and how it
contributes to an ecosystem
• Example: “The red fox's habitat might include forest edges,
meadows and the bank of a river. The niche of the red fox is
that of a predator which feeds on the small mammals,
amphibians, insects, and fruit found in this habitat. Red foxes
are active at night. They provide blood for blackflies and
mosquitoes, and are host to numerous diseases. The scraps left
behind after a fox's meal provide food for many small
scavengers and decomposers.”
Competition
• Competition- when
organisms attempt
to use the same
limited ecological
resource in the
same place at the
same time
o Example: the roots of
different plants
compete for water,
nutrients, and space
in the soil
Types of Competition
• Intraspecific- competition
between members of the same
species
• Interspecific- competition
between members of different
species.
The Competitive Exclusion
Principle
• Idea that no two species can occupy
exactly the same niche, in the same
habitat, at the same time
• If two species try to do this, one of
three things can happen:
1. 1 species will compete better for the niche and the other
species will die out
2. 1 species will compete better for the niche and the other
species will move away
3. The two species will split or share the niche. Ex: rainforest
lizards that eat the same bugs can occupy different parts
of the forest
Predator-Prey
Relationships
• Predation: an interaction in which one
animal (the predator) captures and feeds
on another animal (the prey)
• Predators can affect the size of prey
populations in a community and determine
the places prey can live and feed.
• Give an example in our ecosystem
Herbivore-Plant
Relationships
Herbivory: an interaction in which one animal (the
herbivore) feeds on producers (such as plants)
• Herbivores can affect both the size and distribution
of plant populations in a community and determine
the places that certain plants can survive and
grow.
• Give an example in our ecosystem
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Graphing Community
Interactions
What is shown in this graph?
Use the graph to answer the two questions
below it in the notes.
Keystone Species
• Keystone Species: a single species that is not usually
abundant in a community yet exerts strong control
on the structure of a community.
Keystone Species
• A species whose presence is important for the
structure of a community
• Example:
Kelp
Sea Urchin
Sea Otter
Due to
hunting
Provide shelter and
food for other animals
What will happen to this community?
Sea otters were a keystone species!
Symbioses
• Any relationship in which two species live
closely together is called symbiosis
• Three main classes of symbiosis:
o Mutualism
o Parasitism
o Commensalism
Mutualism
• A relationship in which
both species benefit
• Example: clown fish live in
sea anemones.
o Clown fish are
protected from
predators by hiding
inside the stinging
anemone
o The anemone is
protected from being
eaten by the clown
fish who wants to
defend its home
Parasitism
• When one organism lives in or on another organism
and harms it by obtaining all or part of its nutritional
needs from the host organism.
• Example: Fleas feed on blood and skin of
their hosts; cause discomfort and could
transmit disease
Commensalism
• One organism benefits and the other is neither
helped nor harmed
• Example: barnacles (small ocean animals) live on
whales. They do not harm the whale but the
whale’s swimming allows the barnacles to get
constant food particles from the water.