Transcript It tells an evolutionary story of common ancestors Regents Biology

Evidence for Evolution
by
Natural Selection
Regents Biology
2006-2007
What is evolution?
 Evolution is
the gradual
change in a
species over
time.
Regents Biology
Isn’t evolution just a theory?
A theory is a well-supported
____________, testable
_______,
explanation of phenomena that have
occurred in the natural world, like the
theory of __________________,
gravitational attraction
cell
________,
theory and _____________.
atomic theory
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http://www.avgoe.de/StarChild/DOCS/STARCH00/questions/apple_falling.gif
http://sixthsense.osfc.ac.uk/chemistry/atomic_structure2/atom.gif
Evidence supporting evolution
 Fossil record
 Anatomical record
 Molecular record
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1. Fossil record
Fossils show a series of
organisms have lived on
Earth over a long period of
time
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Fossils tell a story…
the Earth is old
Life is old
Life on Earth has changed
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Evolution of birds
Today’s organisms
descended from
ancestral species
Fossil of Archaeopteryx
 lived about 150 mya
 links reptiles & birds
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We found the fossil!
Land Mammal
?
?
?
Complete series
of transitional
fossils
Someone’s idea of a joke!
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ButBiology
the joke’s
on them!!
Ocean Mammal
?
2. Anatomical record
Animals with different
structures on the surface
But when you look under
the skin…
It tells an evolutionary story
of common ancestors
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Compare the bones
 The same bones under the skin

limbs that perform different functions
are built from the same bones
How could these
very different animals
have the
same bones?
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Homologous structures
 Structures that come from the same origin
 homo- = same
 -logous = information
 Forelimbs of human, cats, whales, & bats

same structure
 on the inside

different functions
 on the outside

evidence of common ancestor
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Vestigial organs
 Hind leg bones on whale fossils
Why would whales
have pelvis & leg
bones if they were
always sea creatures?
Because they
used to
walk on land!
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Vestigial organs
 Structures on modern animals that have no
function
remains of structures that were functional
in ancestors
 evidence of change over time

 some snakes & whales have pelvis bones & leg
bones of walking ancestors
 eyes on blind
cave fish
 human tail bone
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Comparative embryology
 Development of embryo tells an
evolutionary story

similar structures during development
all vertebrate embryos have a “gill
pouch” at one stage of development
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3. Molecular record
 Comparing DNA & protein structure

everyone uses the same genetic code
(DNA)!
Human
Macaque
Dog Bird
Frog
Lamprey
8
32 45
67
125
 compare common genes
 compare common proteins
0 10 20 30 40 50 60 70 80 90 100 110 120
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Building “family” trees
Closely related species are branches on the tree —
coming from a common ancestor
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Rate Yourself
 4 Apply concepts of natural
selection and evolution by
creating a scenario that
demonstrates the ideas
 3 Explain how natural selection
leads to evolution.
 2 Describe how the evidence
supports evolution.
 1 Identify evidence for evolution.
Regents Biology