Transcript Habitats and Niches

Habitats and Niches`
Habitats
o
o
Organisms require certain things in order to
survive such as food, light, shelter, and
water.
An organism’s habitat is the area where it
can survive because it has these
requirements in large enough amounts to
support populations of the organism.
o A habitat is the environment where an
organism lives.
Niche


Pronounced “N-itch”
A niche is an organism’s way of life.
In includes the habitat, the food it eats,
and all other organisms it interacts
with.


Another way to think about it is the
organism’s job.
Often a specific niche leads to evolution
of similar traits.
Niche

Fundamental niche

All resources that could be used in absence of
competition.
Realized Niche
Realized niche
Resources actually used in the
presence of competitors.
Niche Overlap
o
When the niche of two species
overlaps and competition is apparent.
Competition is Expensive!
o
Organisms try to avoid it by getting
M.A.D., they would prefer to:
o
o
o
Move
Adapt
Die
Resource partitioning
o
o
It helps competing
species share a
resource.
Occurs when
species require
different parts of the
same resource.
Competition and niches

Competitive exclusion
o
If two species, with the same niche, coexist in the
same ecosystem, then one will be excluded from the
community due to intense competition.
The Grey Squirrel
The Red Squirrel
The Red Squirrel is native to
Britain, but its population has
declined due to competitive
exclusion, disease and the
disappearance of hazel coppices
and mature conifer forests in
lowland Britain.
The Grey Squirrel - was
introduced to Britain in about 30
sites between 1876 and 1929. It
has easily adapted to parks and
gardens replacing the red squirrel.
Niches and resources



Resource partitioning
avoids competition;
Realized niches divide
resources (insects)
among several species
 woodpeckers,
nuthatches, &
creepers.
Each species evolved &
adapted to specialized
diet.
Galapagos Finches
-from Grant 1986
But…

While there are many
habitats on the Earth, not
all organisms can live in
one habitat. Each habitat
has a limiting factor.

The limiting factor is one
or more resources that
controls the amount of
organisms in the habitat.
Carrying capacity

Since every habitat has a
limited number of resources,
scientists are able to
establish a carrying capacity
for each area.


The carrying capacity is the
maximum number of organisms
that can survive over a long
period of time in one area.
Because there are limits like
this to any habitat, organisms
begin to compete for
resources.
The End!