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Natural Selection
Natural Selection –
• the processes
by which
individuals with
favorable traits
survive and
reproduce,
passing their
traits on to the
next generation.
Animals with unfavorable traits
(ex. poor eyesight, hearing, sense
of smell, etc.) therefore do not
• . survive to pass on their genes
Charles Darwin –
• developed the theory
of natural selection.
He believed that
because of natural
selection, these traits
of survival
accumulated in a
population of a
species and therefore
allowed the species to
adapt and flourish in
its environment.
4 min
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4 Steps of Natural
Selection:
• Overproduction
• Genetic Variation
• Successful
reproduction
• Struggle to survive
Overproduction –
• organisms
often have
more offspring
than could
survive long
enough to
become adults
Genetic Variation –
•
No 2 organisms in
any population have
the exact same traits.
Some of these traits
improve the chances
the organism will
survive (adaptations)
and other traits lower
the chances of
survival.
Successful Reproduction –
• organisms
must be able to
find a mate to
reproduce and
pass on their
genes to the
next
generation.
Struggle to Survive –
•
organisms within a population must
compete for food, water, and living space.
Naturally, an environment cannot support
ALL individuals in a population. Other
individuals may be killed by predators or
disease.
Obstacles to Survival
•
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Naturally rare
Have specific food needs
Have specific nesting requirements
Interfere in some way with human activity
Sensitive to change
Has to compete with non-native species
Have small broods
Have long gestation period.
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