Transcript 2010: Evidence for Evolution

Evidence for
Evolution
Descent with Modification
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Over time, natural selection produces
different organisms
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Different structures
Different niches
Different habitats
Species today look different from their
ancestors
Descent with Modification
Descent with modification also implies that all
living organisms are related to each other
 Common descent- all living things were
derived from common ancestors
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Evidence for Evolution
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Adaptations: changes in a species that occur
over a long period of time that make a
species more successful in an ecosystem
Darwin’s Evidence for Evolution
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Fossil Record
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By comparing fossils from older rock layers to
fossils from newer rock layers, scientists can
document that life on earth has changed.
Fossils
Darwin’s Evidence of Evolution
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Homologous Body
Structures
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Features with a common
evolutionary origin
similar in arrangement
and/or function.
Darwin’s Evidence of Evolution
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Analogous Structures: Have similar
arrangement and/or function but do not
have a common evolutionary origin.
Evidence for Evolution
Vestigial organs: Organ that doesn’t
serve a useful function anymore
 The presence of these organs may not
affect the organism’s ability to survive
 Natural selection will not eliminate that
organ
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Examples of Vestigial Structures
Wings on flightless birds
 Eyes on blind fish
 The human appendix
 Hind leg bones on whales
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Darwin’s Evidence of Evolution
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Similarities in
Embryology
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Embryos of many
animals with a
backbone are very
similar
The same group of
embryonic cells
develop in the same
order and patterns in
all vertebrate