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Natural Selection and
Adaptations
OBJECTIVES
• Today, you will be able to…
– Explain the process of evolution by natural
selection
– Explain adaptation
What exactly is “evolution” in THIS
class?
• Evolution- a change in the GENETIC
characteristics of population from one
generation to the next
• “Change over time”
• NOT
“Humans evolved from monkeys”
How does Evolution occur?
• Through Natural selection….
• That is why it is called “The theory of
Evolution by Natural Selection”
Natural Selection
• Process by which individuals that are better
suited to their environment survive and
reproduce most successfully
• “survival of
the fittest”
Peppered Moth
• Before the Industrial
revolution, the peppered
moth in New England was a
light gray color and blended
in with the lichens that
covered trees.
BEFORE
AFTER
Example of Natural Selection
After the start of
the industrial
revolution, the air
was much more
polluted.
This caused the
lichens to die off.
This cause the
dark peppered
moths to increase
in population.
How does this happen?
• Did the moths magically change colors?
This is how it happened…
• The moth DID NOT magically change colors.
• The light colored moths did not blend in with
the trees (because they had no lichens).
• The light colored moths were easily eaten by
birds.
• The dark moths were now better camouflaged.
• The dark moths were better suited for their
environment and were able to survive,
reproduce, and increase in population size.
Quantitatively (Numbers)
ADAPTATIONS
What is an “adaptation”
• Think about the word “adapt”
• Adaptation- inherited (mutations) characteristics
that increase an organism’s chances for survival.
• Examples:
–
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–
–
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Bird Beaks
Mimicry
Camouflage
Hibernation
Migration
Ex: Darwin’s Finches
• Charles Darwin-(1800s) a naturalist who developed
the theory of Evolution via Natural Selection.
• He observed finches on the Galapagos Islands (as
well as many other animals)
• Through observation, he developed the idea that
things change overtime and become better suited
for their environment.
• Finches- lived on different islands; he noticed their
beak size was determined by which food source
was available
Darwin’s Finches-What do you think
they eat?
What type of food does this bird eat?
Examples of Adaptations
Mimicry
Camouflage
What’s the difference?
• Mimicry- when an animal looks like something
else that is meant to be seen (not hidden)
• Camouflage- hides an animal (or something
else). If an animal matches its background, it is
harder to see.