Transcript Classification - Charleston County School District

Classification
Evolution & The Ocean
• Evolution: change
• Revolutionaries: Charles Darwin & Alfred
Wallace
Darwin’s Main Points:
1. In any group of organisms, more offspring are
produced than can survive to reproductive
age.
2. Random variations occur in all organisms.
3. Some traits increase probability that
organisms possessing them will survive.
(Favorable Traits)
Darwin’s Main Points:
4. Because bearers of favorable traits are more
likely to survive, they are also more likely to
reproduce successfully than bearers of
unfavorable traits. Thus favorable traits tend to
accumulate in the population; they are selected.
Darwin’s Main Points:
5. They physical and biological (natural)
environment itself does the selection. Favorable
traits are retained because they contribute to
the organism’s success in its environment. These
traits show up more often in succeeding
generations if the environment stays the same.
If the environment changes, other traits become
favorable.
Theory of Evolution & Natural
Selection
• How do entirely new traits come about?
– Spontaneous mutations
• Mostly unfavorable
– Tuna example
*Special Note*
• Although mutations occur randomly, evolution
by natural selection is anything but random.
Evolution & Natural Selection
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Organisms don’t want to change
Individual organisms don’t evolve
Happens over generations
Adaptations occur