1 more than an eyewitness evidence for evolution
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More Than An EyeWitness
Evidence for Evolution
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Sources of Evidence
From the fossil record
From studies of anatomy
From studies of embryology
From studies of DNA
From observationBiochemistry
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EVIDENCE FROM FOSSILS
From the fossil record
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Transitional Organisms
• If evolution has occurred in the past there should be evidence of transitional organisms in the fossil record.
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Archeopteryx
• Archeopteryx shows evidence of the evolution of birds from reptiles….there is evidence of feathers, a characteristic of birds, and claws, a characteristic of reptiles.
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EVIDENCE FROM ANATOMY
From studies of anatomy
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Identify how each organism uses its forelimb
Frog Lizard Bat Human Lion Sea Lion
bird
balance Walking flying Multiple
uses
walking swimming flying
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Anatomical Studies show• Homologous parts – similar in structure but not
necessarily function – evidence of evolution from common ancestor
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Anatomical studies show...
• Name two other organisms that have the ability to fly but have wings very different than those of the bird or the bat?
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Analogous structures• Butterflies or insects have wings but they are very
different from the birds. These organisms do not have a common ancestor but have adapted to a similar environment. Again evolution explains the similarities.
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Anatomical studies show• Vestigial parts – why does a whale have a pelvis and
femur bones if it has no hind limbs?
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Vestigial structures
• Why does this salamander have eyes if it never sees the light of day?
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Vestigial structures
Ear muscles Wisdom teeth Appendix
Human vestigial structures
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Why do these structures occur?
• These structures may be homologous to ones that had a function in the ancestors of these organisms thus suggesting their evolution from this common ancestor.
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Anatomical Studies
• Anatomical studies of cells show a commonality in structure of the cell membrane among almost all living things. Does this suggest a common ancestor for all life?
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EVIDENCE FROM EMBRYOLOGY
From studies of embryology
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Embryology Studies• Even though it may not be apparent during the first stage (A)
these five organisms are very different when born and at later stages of embryonic development. Why do they look so similar initially?
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Stage
(A)
A B C D E
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Did you THINK about it?
Did you write down all your Guesses?
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Embryology Studies
• The organisms are:– Fish
– Salamander
– Chicken
– Rabbit
– Human
– Why would these five, so different looking organisms at birth, look so similar before birth?
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More about embryological studies
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EVIDENCE FROM BIOCHEMISTRY
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Studies of Biochemistry
Species Sequence of Amino Acids in the Same part of the Hemoglobin Molecule
Human Lys-Glu-His-Iso
Horse Arg-Lys-His-Lys
Gorilla Lys-Glu-His-Lys
Chimpanzee Lys-Glu-His-Iso
Zebra Arg-Lys-His-Arg
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Which organisms appear to be more closely related to each
other?Human and chimpanzee have no
differences in their amino acid sequence suggesting their close evolutionary
relationship, they have a more recent common ancestor. Studies of other
chemicals, like proteins used in digestion, show similar comparisons in these
organisms.
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EVIDENCE FROM DNA
From studies of DNA
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DNA
• The sequence of the nucleotides making up their DNA would also be similar because DNA determines the sequence of amino acids in proteins.
From studies of DNA
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DIRECT OBSERVATION OF EVOLUTION OCCURRING IN MODERN DAY ORGANISMS
From observation
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Observations of Evolution in modern organisms
• Mosquitoes resistance to insecticides
• Bacteria resistance to antibiotics
• New strains of Plasmodium that cause Malaria
• New strains of TB (tuberculosis)
• Peppered moth
• Darwin finches
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Has and Does Evolution Occur?
• Scientists do not dispute that evolution does occur. Evolution is a FACT.
• How evolution occurs is not completely understood.• Charles Darwin explained how evolution occurred
through natural selection. Natural selection is a well documented THEORY uniting all of biology.
• Modern evolutionary theory uses ideas of genetics, particularly mutations, to help explain how evolution may occur. (Darwin didn’t know about mutations.)
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