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Natural Selection
Darwin’s Simple Observations

Darwin’s theory of natural selection was
the result of noting and connecting several
observations of phenomena in nature.
Note: The things Darwin saw were common
everyday things in nature – nothing special –
in fact, you have probably noticed many of
the same things yourself!
 Darwin had four observations that led him
to formulate his theory of evolution by
natural selection.

Genetic Variation


The traits for a
population show
variation.
Most of this
variation is
inherited by
offspring from
their parents.
Population Stability


Far more offspring
are produced than
what can survive
(due to limited
resources).
Populations sizes
tend to remain
relatively stable
(Psst…”Stable”
means the same.)
Darwin’s Inferences
1. The members of a species must compete for
survival due to the lack of resources.
YUMMY!
YUMMY!
YUMMY!
YUMMY!
Darwin’s Inferences
2. The members of the population that have the traits best
suited to the environment will win the competition for
limited resources. (Survival of the Fittest)
WINNING!
Darwin’s Inferences
3. The best fit individuals will survive and reproduce so the
favourable traits will become more and more prevalent
within the population over time.
That’s All I Got…