Transcript Competitive Exclusion

17-2: Competition shaping
communities
• The competition for
common resources, very
little resources, in one
community determine the
nature of that community
Niche
• The functional role of a species,
its activities and relationships,
within its ecosystem.
• Each organism has its own
niche, its own unique way that it
interacts with its environment,
biotic and abiotic factors
Fundamental niche
• The total range of
environmental conditions in
which a species can survive
and make use of
Example: Fundamental
niche
Realized Niche
• The part of the
fundamental niche that a
species actually occupies.
Example: Realized Niche
Character displacement
• When competing species
become physically different
due to its realized niche
• Believed to be caused by
evolution and the species
adaptation
Example of Character
displacement
Why are the
beaks
different?
Competition results
• Where two species exist, a
species that is a better
competitor will drive out the
second species
• Competitive Exclusion:
Elimination of one species in
an area
Example: Competitive
exclusion
• Chthamalus stelatus
lives in shallow
water and is
exposed to air
during low tide
• Its Fundamental
Niche is shallow and
deep Ocean water
Example: Competitive
exclusion
• Balanus.
Normally
occupies lower
Ocean depths.
• Its Fundamental
niche is the
lower Ocean
depths
Example: Competitive
exclusion
• Balarus can out
• Chthamalus
stelatus can live in
both shallow and
deeper depths, but
cannot out compete
Balarus for space.
This makes its
realized niche in the
shallow portion of
the ocean
compete Chthamalus
stelatus for space, but
cannot survive when
exposed to air during
low tide. This makes
its fundamental and
realized niche the
deeper Ocean levels
Principle of competitive
exclusion
• The species that uses the
resources more effectively
will eventually exclude the
other
• If both species niches do not
overlap too much they can
both survive
A change of number of
Organisms in an ecosystem
• Predation lessons the effects of
competition.
• Predators keep the prey numbers in
check.
• This is important because some prey
can out compete other organisms for
available resources.
• This would result in less species
diversity for an ecosystem
Example: Aleutian Isles
• The disappearance of the otter, due to
being eaten by orcas, allowed sea
urchins to thrive.
• Sea urchins ate all the kelp which left
no food for many fish in this ecosystem
• With no food for the fish they left and
the number of organisms in the
Aleutian Isles shrunk