Download Evolution 07 Natural Selection

Evolution 07 Natural Selection
Evolution: Natural Selection
Warm Up
Objectives
• Explain how natural
selection leads to
evolution.
Predict how the this beetle
population may change in this
environment, then explain your
reasoning. Use the words variation,
adaptation, selective pressure, and
change in your answer.
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Selective Breeding: Evidence for Evolution
• Natural variation
occurs in the wild
population
• Seeds for the next
generation are chosen
only from individuals
with the most desirable
traits.
• Repeat this process for
several generations.
Selective breeding is an example
of artificial selection.
Artificial selection helps us
understand how adaptations
evolve in nature.
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Natural Selection
The process whereby organisms better adapted to
their environment tend to survive and produce
more offspring.
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Natural Selection: Peppered Moths Simulation
http://peppermoths.weebly.com/
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Natural Selection: Peppered Moths Simulation
Discuss with your group
members
http://peppermoths.weebly.com/
1. Describe the environment your
group chose.
2. How did the moth population
initially vary?
3. Describe the natural selective
pressures of this environment.
4. How did the selective pressures
influence the moth population?
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Natural Selection: Peppered Moths
Industrial melanism arose by chance in
the population of peppered-moths.
In an environment with trees polluted
with soot, industrial
melanism is
advantageous because it camouflages
black peppered moths against predators.
As a result, black peppered moths
survived better and reproduced more
offspring than white peppered moths.
Over time, the population black
peppered-moths increased as the white
peppered moths decreased.
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Natural Selection: Peppered Moths
Just one example! Not limited to not being seen
by predators. Other examples include:
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Ability to live with limited amounts of water
Ability to live in water
Ability to catch food
Ability to make food
Ability to see with low light
Ability to climb
Ability to protect self
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Natural Selection
1. Species tend to produce more offspring than the
environment can support.
2. Struggle for existence in which some individuals
survive and some die.
3. Natural variation within a population.
4. Some individuals are better adapted than others.
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Natural Selection: Peppered Moths
5. Better adapted individuals tend to survive and
reproduce, less well adapted individuals tend to die/
reproduce less  each generation contains more
offspring from better adapted individuals.
6. Individuals that reproduce pass on characteristics to
their offspring.
7. The frequency of characteristics that make individuals
better adapted increases, so species change and become
better adapted.
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Problem of the day
Explain how natural selection leads to
evolution.
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