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The Theory of Evolution
Jean Baptiste Lamarck ~ 1809
Recognized that species were not constant. Believed species
changed over time.
1.
The Law of Use and Disuse- States that the more something
is used by an organism, the stronger it becomes. & vice versa
2.
Inheritance of Acquired Characteristics- Assumes that
characteristics acquired through use and disuse could be passed
on to offspring.
August Weismann
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Disproved Lamarck
Cut the tails of 100’s of mice
Bred the tailless mice
All of the offspring had tails
Charles Darwin ~1800’s
1.
2.
Begins a 5 year journey on the HMS Beagle to
catalog plant and animal species around the
world.
Collects evidence for evolution based on:
a.
b.
Fossil evidence
Observations of subtle changes in:
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3.
Plants
Insects
Birds (i.e Darwin’s Finches @ Galapagos)
1859 ~ Published landmark book On The
Origin of Species.
6 Main Points of Darwin’s
Theory
1.
2.
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5.
6.
Overproduction
Competition
Variation
Adaptation
Natural Selection
Speciation
Darwin’s Finches
An example of speciation from the Galapagos
1.
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5.
6.
Each species gives birth
to more babies than the
environment can support
Individuals compete for
limited resources
Phenotypes vary in each
population
Some variations in the
population have
advantages over others.
Nature causes the weak
to die before they
reproduce.
The changes can be so
great to cause new
species to arise.
Galapagos Tortoises
There are 14 “races!”
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Saddleback Tortoise:
Smaller
Found on “lower” more
arid islands
Food is less available
Notch in the shell to
allow better reaching for
food
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Dome Shelled Tortoise:
Larger
Found on mountains
More rain = more
vegetation
Easier habitat for
foraging.
No “notch” in shell.