Download THAT is evolution!

How Evolution Works
Natural Selection
Evolution Music Video

http://www.youtu
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Natural Selection
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Similar to artificial
selection
Traits being selected
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maximize survival to
adulthood
reproductive success
in the wild
Rapid Reproduction

Every organism
produces more offspring
than the current
generation.

Even elephants, the
slowest reproducing
animals, have three
times as many offspring
as the current
population each
generation.
Most Die

This population growth
potential is kept in check
by limiting factors.

There are more
organisms born
(reproduced) by every
species than can possibly
survive to reproduce
themselves and most of
them do die.
Variation

Variation exists in
every population.
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Some fish are bigger
than others.
Some fish have more
stripes.
Some fish are faster.
Inherited Variation

Some variations are
inherited. DNA.
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Big fish have big
baby fish.
Striped fish have
striped baby fish.
Fast fish have fast
baby fish.
Natural Selection

An organism that has
a variation determined
by a genetic trait will
produce more
offspring with that
same trait if the trait
helps it:
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survive to reproduce
be selected by a mate
produce more
offspring
Evolution!
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The offspring, also
possessing the
favorable trait, will in
turn have a better
chance of surviving
and being
reproductively
successful.
The trait will increase
in frequency in the
population.
THAT is evolution!
How Evolution Works - Summary

Organisms reproduce more offspring than can possibly
survive.

There is variation in every population caused by
inheritable, genetic, differences

Most organisms die before they reproduce.

Ones with favorable variations are more likely to
survive to reproduce.

The next generation looks like (has more variations
similar to) the survivors that reproduce from the
previous generation.
Natural Selection – pocket mouse