Natural selection is the process by which organisms with traits that help them survive and reproduce in their environment become more common over generations. When resources are limited, competition arises between organisms. Those with useful adaptations, like camouflage, are more likely to live on and pass their traits to offspring. Over time, natural selection leads populations to become dominated by organisms with adaptations suited to the environment.

1. Natural Selection
Vocabulary

2. Resources:
• stuff in the environment that is
needed for survival
• often limited (can be used up)

3. environment
air
food
mate
shelter
organism

4. Competition:
The effort of 2 or more organisms
acting independently to get
resources that are in short supply.

5. Variation:
• Differences in shape, structure, or
function
• Caused by sexual reproduction or
mutation
Dangling earlobe Attached earlobe

6. Adaptation:
A useful trait that helps an organism
to survive, and which gives it an
advantage in its environment.
camouflage

7. Overpopulation:
• Too many organisms in one
environment
• Can lead to competition

8. Natural Selection Concepts

9. Overpopulation can lead to
competition.
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10. Due to competition, some
organisms (with useful traits)
will live on…
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...but others will die.
Also called “survival
of the fittest”

11. The usefulness of a trait depends
on the resources and environment.
brighter stripes
(+) attracting a
mate?
(-) more visible
to predators?
skinny body
(+) hide or live in
small holes?
(-) not so strong
for defense?
Speedy swimmer
(+) fast escapes
(-) needs lots of
energy (food!)

12. Organisms that have useful
traits (adaptations) will
survive and then reproduce.
They pass the traits on to their
offspring.
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14. END RESULT:
The environment now has a lot
more organisms that have
certain traits.
This is NATURAL SELECTION.
(Nature chooses the traits that
will increase in the population.
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