Download Chapter 13 Section 2 - Warren's Science Page

Evidence of Evolution
Grade 10 Biology
Spring 2011
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Describe how the fossil record supports
evolution
Summarize how biological molecules such as
proteins and DNA are used as evidence of
evolution
Infer how comparing the anatomy and
development of living species provides
evidence of evolution
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Fossils show a pattern of
development from early
ancestors to modern
descendents
Offer direct evidence that
evolution has taken place
Provide an actual record of
Earth’s life forms
Change over time
(evolution) can be seen in
the fossil record
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Fossil intermediates linking great groups of
organisms have been found
Between fish and amphibians
 Between reptiles and birds
 Between reptiles and mammals
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Based on a large body of supporting evidence,
three major points:
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Earth is about 4.5 billion years old
Organisms have inhabited Earth for most of its
history
All organisms living today share common ancestry
with earlier, simpler life forms
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The fossil record, the record of evolution of life,
if not complete
Many species have lived in environments where
fossils do not form
Most fossils form when
organisms and traces of
organisms are rapidly
buried in fine sediments
deposited by water,
wind, or volcanic eruptions
Organisms also decay at different rates
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The fossil record will never be complete, but it
still presents strong evidence to support
evolution
Paleontologist: scientists who study fossils
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Discover fossils and analyze sediments around it
Radiometric dating of rocks and minerals, can
arrange the fossils in order from oldest to youngest
Shows orderly pattern of evolution
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Comparisons of anatomy of different types of
organisms often reveal basic similarities in
body structures even though the structure’s
function may be different
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Vestigial structures: bones that are present in
an organism but have been reduced in size and
either have no use or have a less important
function than they do in the other related
organism
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Ex. Hind limbs of whales
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Homologous Structures: are structures that
share a common ancestry
As different groups of vertebrates evolved, bodies
evolved differently
 Similarities in bone structure can still be seen
 Similar structure in two organisms can be found in
the common ancestor
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Development of
embryos shows
evolutionary
history
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In some point of
development all
vertebrate
embryos have a
tail, buds that
become limbs, and
pharyngeal
pouches
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If species have changed over time, then the
genes that determine species’ characteristics
should also have changed by mutation and
selection
Changes would have become part of their
genetic instructions
Changes in a gene’s nucleotide sequence
should build up over time
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Prediction was first tested by analyzing amino
acid sequence of similar proteins found in
several species
Of evolution occurred, then species descended
from a recent common ancestor should have
fewer amino acid differences between their
proteins than do species that share a common
ancestor in more distant path
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i.e. humans and chimps should have fewer
differences in their proteins than humans and frogs
Hemoglobin Comparison
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Species that are thought
to have shared a common
ancestor more recently
(humans and gorillas)
have few amino acid
sequence differences
Species that are though
to have shared a common
ancestor more distant
past (humans and mice)
have many amino acid
sequence differences
Species
A.A differences
from human
hemoglobin
protein
Gorilla
1
Mouse
8
Rhesus monkey
27
Chicken
45
Frog
67
Lamprey
125
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This pattern, doesn’t hold true for all proteins,
some proteins may evolve more rapidly than
others
Evolutionary histories are generally not
inferred from any single protein’s amino acid
sequences
More accurate evolutionary histories are based
on large numbers of gene sequences
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These evolutionary histories based on DNA
sequences tend to be very similar to
evolutionary histories inferred by biologist
based comparative anatomy and evidence from
fossil record
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Game:
http://biodude.wikispaces.com/file/view/Ev
olution+Review+Game.pdf