Transcript Natural Selection, Adaptations, and Niches

Natural Selection,
Adaptations, and Niches
Essential Targets:
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Define the terms: Natural Selection,
Adaptation, and Niche
Explain how adaptations benefit an organism
Identify and describe the three types of
interactions between organisms in a
community
What is Natural Selection?
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Every organism has some
unique characteristics that
enable it to live in its
Environment
In response to their
environment, species
evolve, or change over time
The changes that make
organisms better suited to
their environment become
common in that species by a
process called natural
selection
Charles Darwin 18091882
“Bummer of a birthmark, Hal.”
Example of Natural Selection
One of the first examples of selection in nature was
provided by the peppered moth.
Up until 1850, the dark form of
the peppered moth had been very
rare in England.
By 1895, the dark form made up
98% of moth populations in some
industrial areas.
What was the explanation
for the increased frequency
of the dark form in
industrial areas?
The hypothesis was that pollution had
darkened the trees by killing the
lichens, making the light phenotype
more susceptible to bird predation.
We can test this
hypothesis by asking
what should be
happening today since
pollution has been
reduced by legislation.
What would you predict?
Do the data in this graph support the
pollution/selection hypothesis?
Natural Selection
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Those species that live longer live to reproduce
and pass along those characteristics (traits)
Natural Selection leads to “?”
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The results of natural selection are
adaptations
The behaviors and physical characteristics of
species that allow them to live successfully in
their environment
Every organism has a variety of adaptations
that are suited to its specific living conditions.
These adaptations create a unique role for the
organism in its ecosystem
Adaptations
Adaptation: A physical feature or
behavior that allows an organism to
survive in its environment
Lynx vs. Bobcat
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Canada Lynx (Lynx
lynx
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Bobcat (Lynx rufus )
Lynx vs. Snowshoe Hare
Interaction of Organisms
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1.
2.
3.
Some adaptations involve how organisms
interact.
Competition
Predation
Symbiosis
Competition
Swift Fox
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Coyote
Gray Wolf
Competition - the struggle between organisms to
survive as they attempt to use the same limited
resource.
Predation
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Predation - one organism kills and eats another organism.
The organism that does the killing is the predator. The
organism that is killed is the prey. Predators have adaptations
that help them catch and kill their prey. Prey organisms have
adaptations that help them avoid being caught and eaten.
Symbiosis
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Symbiosis - a close relationship between two
species that benefits at least one of the
species.
1.
2.
3.
Mutualism (both species benefit)
Commensalism (one species benefits. Other is
not effected)
Parasitism (one species benefits. Other is
harmed)
Niche
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An organism’s particular role in its habitat, or
how it makes its living, is called its niche
A niche includes the type of food the organism
eats, how it obtains this food, which other
species use it as food, when and how the
organism reproduces, and the physical
conditions it requires to survive.
Understanding an ecological niche
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The idea of an ecological
niche is very simple. You
just need to know where
the animal or plant lives
and what it does.
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Oak trees live in oak
woodlands. The oak
woodland is the habitat. So
if you were writing a letter
to an oak tree you would
address the letter to:
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Mr. Deciduous Oak Tree,
The Oak Forest,
Maine, USA.
Understanding an ecological niche
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What do oak trees do? If you can answer
that question you know the oak trees
"profession" or its ecological niche.
Perhaps you think that oak trees just stand
there looking pretty and not doing vey
much, but think about it.
1.
absorb sunlight by photosynthesis;
absorb water and mineral salts from the
soil;
provide shelter for many animals and other
plants;
act as a support for creeping plants;
serve as a source of food for animals;
cover the ground with their dead leaves in
the autumn.
2.
3.
4.
5.
6.
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These six things are the "profession" or
ecological niche of the oak tree; you can
think of it as being a kind of job
description. If the oak trees were cut down
or destroyed by fire or storms they would
no longer be doing their job and this
would have a disastrous effect on all the
other organisms living in the same habitat.
Understanding an ecological niche
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Now you get to try:
Where does this species live?
What does this species do?
Understanding an ecological niche
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Now you get to try:
Where does this species live?
What does this species do?
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Questions?
Essential Targets:



Define the terms: Natural Selection,
Adaptation, and Niche
Explain how adaptations benefit an organism
Identify and describe the three types of
interactions between organisms in a
community