Transcript The Theory of Evolution

Bell Ringer – 1/11/2007
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What can happen to a population when the
environment changes?
The Theory of Evolution
History and evidence for…
Evolution
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Gradual change in species through
adaptations over time
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What are adaptations?
Charles Darwin (1809-1882)
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English Naturalist
Was NOT the first to propose that species
evolve
Was the first to propose how they evolve
Natural Selection
Darwin’s Voyage
Facts that Darwin observed…
1.
Without limiting factors, populations grow
exponentially
2.
Populations tend to fluctuate above and
below carrying capacity
3.
Resources are limited. Individuals struggle
to survive
Facts that Darwin observed…
4.
Individuals are unique; variation exists
within a population
5.
Those individuals that are able to survive
and reproduce keep their variations in the
population
Darwin Also Observed
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Artificial Selection
Dogs being bred for certain traits
Horses being bred for speed
Cotton and wheat being bred for size
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Darwin theorized that there was a force in
nature that worked just like artificial selection
(natural selection)
Muy Importante!
Natural Selection acts
on variations that
exist in a population
Quick Review
Quick Review
Quick Review
Speciation – formation of new species
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Geographic Isolation
Speciation
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Geographic isolation leads to reproductive
isolation
Populations become so different that they
can no longer interbreed
The presence of multiple niches speeds
speciation
Evidence for Evolution
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Structural Adaptations – favorable
adaptations are selected for
Camouflage
Mimicry
Etc.
Evidence for Evolution
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Physiological Adaptations – changes to
an organisms metabolic process
Evidence for Evolution
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Anatomy – homologous structures
Evidence for Evolution
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Anatomy – analogous structures
Evidence for Evolution
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Anatomy – vestigial structures
Evidence for Evolution
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Embryology – comparing embryos
Evidence for Evolution
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Biochemistry – DNA, ATP, Enzymes
Evidence for Evolution
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Fossils – show change over time
Fossils
Horse Evolution