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Theories of Evolution
WHAT ARE SOME THEORIES RELATED TO EVOLUTION?
Time Frame of Evolution
Gradualism
 Slow, continuous change over time.
Punctuated Equilibrium
 Long periods of stability interrupted
by brief periods of change.
Cladograms
An evolutionary tree of
life enabling us to
compare relatedness
through ancestry.
Most Recent Common
Ancestor = Most Similar
Line ending abruptly
before end of
cladogram = Extinct.
Inherited & Acquired Characteristics
Inherited Characteristics
Part of your DNA; born with
this trait.
Acquired Characteristics
Trait developed
throughout lifetime.
Blue Eyes
Good Dancer
Tall
Strong
Freckles
Knowledge of Biology
Straight Hair
Blue Hair/Hi-lights
Lamarck’s Theory of Evolution (WRONG!!!)
Lamarck believed that evolution occurred
through the inheritance of acquired
characteristics.
Organisms developed traits throughout
their lives that helped them survive.
Beneficial traits were passed on to the offspring
of those organisms.
Lamarck’s Theory of Evolution (WRONG!!!)
EXAMPLES:
Giraffes stretch their necks to help them reach leaves
high on the trees, and baby giraffes are born with
long necks.
If you cut the tail off a mouse, it’s babies will be born
without a tail.
If you dye your hair blue, your baby will be born with
blue hair.
Darwin’s Theory of Evolution (RIGHT!!!)
Darwin believed that evolution occurred
through the process of Natural Selection.
Organisms each have unique
traits/adaptations that allow them to survive.
Only the organisms who have the best traits
will survive to pass on their traits to their
offspring. (Survival of the Fittest)
The Origin of Species: The Making of a Theory