Transcript fundamental niche - NWHS Mr. Corsini

Why is how species interact with
each other important?
1. Interactions can affect the distribution and
abundance of species.
2. Interactions can influence evolution.
Competition – when two species share a requirement
for a limited resource  reduces ecological fitness of one
or both species
Types of ecological competition
1. Intraspecific competition – between individuals of the
SAME species
contributes to K (carrying capacity)
2. Interspecific competition – between individuals of
DIFFERENT species
How does interspecific competition affect N?
1
k rats excluded
.8
.6
.4
.2
0
# deer mice captured
control
1978-80
1988-90
(Heske, E. J., J. H. Brown, and S. Mistry 1994)
What is the effect of kangaroo rat competition on deer mice?
Competitive exclusion principle
If two species have the same niche, the stronger
competitor will eliminate the other competitor.
“Complete competitors cannot coexist.”
Some questions to discuss…
Why do kangaroo rats exclude deer mice?
Complete competitors cannot coexist
What if you put more seeds in the environment?
Competitive exclusion is reached more slowly with
more resources, but will still happen
What if you added another resource to the environment?
Stable coexistence requires niche differentiation, these
two species are too similar and would still complete
directly with one another
How does interspecific competition affect N?
Lotka-Volterra equation
Why isn’t this a complete picture of what happens in nature?
A classic interspecific competition experiment
two species of Paramecium
predict the outcome of
interspecific competition
P. aurelia
P. caudata
Gause (1934)
What is the niche?
set of conditions
within which an organism
can maintain a viable
light intensity
population
multi-dimensional
salinity
with as many
dimensions as their
are limiting conditions
okay
ecological
niche
temperature
Fundamental niche depends on physical (abiotic) conditions.
Realized niche depends on biotic as well as abiotic conditions.
What is the realized niche of each barnacle?
What is the fundamental niche of each?
How can we determine the realized niche of each barnacle?
Where do they grow when allowed to compete?
growth
rate
Balanus
realized
niche
low
Balanus
and
Chthamalus
Chthamalus
realized
niche
middle
high
Location in intertidal zone
How can we determine the fundamental niche of each barnacle?
Removal experiments – remove each species and see
where the other grows
Balanus alone
Balanus
fundamental
niche
growth
rate
Chthamalus alone
Chthamalus fundamental niche
low
middle
high
Location in intertidal zone
The niche of a species may contract in the presence of a
competitor species.
This phenomenon leads to resource (niche) partitioning
and coexistence among functionally similar species.
Streams with only
Planaria species A
Streams with only
Planaria species B
Streams with both
Planaria species
What are the fundamental
and realized niches for
each species?
So…competition is one way in which species can
interact with one another.
It can be intraspecific (between members of the same species)
or
It can be interspecific (between members of different species)
When invasive species are introduced to an ecosystem, which
type of competition do you suspect may result in the
reduction of native species populations?
Your assignment
1st choose one invasive species that completes directly with a
native species (interspecific competition). This should not be
a predator/prey interaction.
2nd create an educational “talk” aimed at informing the public
about how this invasive species can cause a decrease in (or in
some cases disappearance of) native populations. This can be
a poster presentation. Include:
-A brief biography on each species
-An explanation of what ecological competition is
-A description of each species fundamental niche
-An explanation describing the competitive exclusion
-One graph showing how the invasive has impacted native
populations