AIM: How do interactions between a
species and its environment define
the species niche.
Do Now: What is a species niche?
Give an example.
HW: Article #1 due Friday
End of notes questions
The environment in one part of an
ecosystem is different from the
environment in another part.
Organisms living in each part of an
ecosystem differ from eachother.
Each organism is adapted to the
conditions in the part of the
environment in which it lives.
Habitat
The place in an
ecosystem where an
organism lives
They can be large or
small depending on
the size of the
organism and how
much it travels
Niche
The role of an organism
in it’s ecosystem
The actions of an
organism define it’s
niche- a niche is more
than an organisms
habitat. It’s also what
the organism does
within a habitat
A niche includes both biotic and
abiotic factors
Biotic Factors (living things)
– Food sources
– Predators
All of the
biotic and
abiotic
factors
taken
Abiotic Factors-nonliving things
together
– Temperature
define the
– Sunlight
organisms
– Water
niche
All members of a species are
adapted to the same habitat
• No two species can share the exact
same niche in the same habitat but
two species can occupy niches
that are very similar
• The different species can live sideby-side because they occupy
different niches
Competitive Exclusion
• If two species try to share the same niche,
they will compete for resources
• One of them will have to move to another
area or the population will die out.
• The extinction of a population in a specific
area due to direct competition with another
species for a resource is called
competitive exclusion
The activity of one species
can help define another
species niche.
Scientist J.H. Connell performed an
experiment to study how one barnacle
species affects the niche of another
Species A- lives on rocks exposed to air
Species B- lives on rocks covered in water
most of the time
He removed all of
species B from a
small area of the
shore
He found that
species A began to
grow on the lower
rocks
Cornell hypothesized that species A
could live on all parts of the shore, but
that species B drove out species A
wherever species B can survive.
The A population was limited to the
higher rocks by B, even though A
could live on all the rocks in the
absence of B
He hypothesized
that the niche of
one species can
affect the niche of
another
Fundamental niche = theoretical niche
•Niche that an organism can ideally have
(wherever it is able to survive)
Realized niche
•The niche that the organism actually
has (Where the organism is really
living)
Niche Diversity
• The number of different niches in an
ecosystem
• Determined by the abiotic factors in an
environment
• Ex:
– Marsh- many organisms, few niches
• Constant abiotic factors
– Desert- few organisms, many niches
• Fluctuating abiotic factors
Predators
•Play an important role in increasing niche
diversity by decreasing the population size of
their prey
•When more resources become available for
another species, a new niche will have been
created
Predator- actively hunts another organism
Prey- the hunted organism
Keystone Predator
A predator that promotes niche
diversity in it’s habitat
1. What is a species niche?
2. What factors help to define a niche? Give
examples of each.
3. What prevents two species from sharing
the same niche? What is this called?
4. Explain the difference between an
organisms fundamental niche and its
realized niche?
5. What is the role of predators in
determining niche diversity?
6. Identify abiotic factors that contribute to
niche diversity.