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Peppered Moths
Year #1
Year #10
How might this change affect the Peppered Moths?
Explain why the numbers of moths changed over time.
Year #1
Light Moths
Dark Moths
556
63
Year #10
Light Moths
Dark Moths
56
638
The Theory of Natural Selection
Over time, those not adapted most likely die
Artificial Selection
• Humans have shown
that breeding can
cause changes over
time
– Dogs, Crops,
Livestock
• Humans (not nature)
have selected
desirable traits
• What’s the point?
Proves that breeding
can lead to change
over a period of time
Pigeons have been bred to enhance
tail feathers….breast feathers…etc…
Wild mustard has been bred by farmers
into numerous other foods
Dog traits have been selected by breeders for
centuries to enhance certain traits.
These kittens
have variations
Not all these
wildebeest will
survive
• Four factors:
1) Overpopulation: more offspring are born than can survive
2) Variation: individuals of a population have differences
3) Adaptation: Some variations allow a better chance of
survival
4) Descent w/ modification: Those with advantages will
reproduce and make more of the population
Darwin Video Clip
The Myth
Which rabbit is best adapted?
Do the dark rabbits turn white?
Struggle for Survival
Predation
Competition
Disease
Clean water
Shelter
Acts of Nature
• Populations do not grow unchecked
• “Limiting Factors” prevent overpopulation
• Fitness: measure of the ability to survive & produce
more offspring
New environments are
continually created.
What happens to life that
has favorable traits to
survive the change?
Changing Environments
Peppered Moths
Year #1
Year #10
How might this change affect the Peppered Moths?
Why would the populations change? Create a hypothesis
to explain why the number of moths changed.
Year #1
Light Moths
Dark Moths
556
63
Year #10
Light Moths
Dark Moths
56
638
Natural Selection in Action:
The Peppered Moth Analysis
Before the industrial revolution, the trees in the forest around Manchester,
England were a light grey/green due to the color of lichens (fungus) on their
trunks. Peppered moths, or Biston betularia, which lived in the area, were
mostly lightly colored with dark spots. However, there was some color variation
between the moths. The most common moth color was light with dark spots and
the least common were dark with light spots. Because there were not enough
resources to support the entire population, the members of this species had to
compete for survival. Their coloring, when against a similar background, served
as camouflage against predators such as birds and lizards, thus increasing
chances of survival.
Natural Selection in Action:
The Peppered Moth Analysis
As the Industrial Revolution progressed, the trees became covered with sulfur
dioxide, turning the trunks dark.
Kobe Kuiz
1)
2)
3)
4)
What is artificial selection?
What is natural selection?
How does natural selection lead to population changes?
Explain why scientists believe the Earth’s environments have
been changing for millions of years.
5) Why don’t populations (such as deer) continue to grow
unchecked?