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TRANSCRIPT
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AIM: How can we know that evolution has
actually occurred?
Warm – up:
How does Darwin explain the presence of organisms alive
today?
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LaMarck• Organisms adapted to their environments
ØThrough acquired traitsØChange in their lifetime
v Use & Disuse: organisms lost parts of their body because they did not use them (like the missing eyes and digestive system of the tapeworm)
v Perfection with Use & Need: the constant use of an organ leads to an increase in size of that organ
ØTransmit acquired characteristics to next generation
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LaMarck• Organisms adapted to their environments
ØThrough acquired traitsØChange in their lifetime
v Use & Disuse: organisms lost parts of their body because they did not use them (like the missing eyes and digestive system of the tapeworm)
v Perfection with Use & Need: the constant use of an organ leads to an increase in size of that organ
ØTransmit acquired characteristics to next generation
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But the fossil record shows…
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Descent with Modification
Darwin’s idea that each species living today arose from a pre-existing
species!
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Hundreds of millions of years passed before atmospheric oxygen levels were high enough to support eukaryotes.
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Evidence Supporting Evolution
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Evidence Supporting Evolution
• Fossils (descent with modification)
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Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry
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Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology
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Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology• Comparative embryology
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Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology• Comparative embryology
• Comparative anatomy
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Fossils as Evidence
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Fossils as Evidence
• A fossil is the remains of organisms that lived in the past.
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Fossils as Evidence
• A fossil is the remains of organisms that lived in the past.
• They are preserved by natural processes (in ice, rock, etc.)
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Fossils as Evidence
• A fossil is the remains of organisms that lived in the past.
• They are preserved by natural processes (in ice, rock, etc.)
• Examples: bones, shells, footprints, imprints
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Fossils as Evidence
• A fossil is the remains of organisms that lived in the past.
• They are preserved by natural processes (in ice, rock, etc.)
• Examples: bones, shells, footprints, imprints
• Generally, found in sedimentary rock that has been quickly covered by silt. Why?
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How old are fossils?
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How old are fossils?
• Relative dating: Fossils can be dated in correlation with the age of the strata (layer of rock) they are in.
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How old are fossils?
• Relative dating: Fossils can be dated in correlation with the age of the strata (layer of rock) they are in.
• Absolute Dating: Using radioactive isotopes (half life) to get a more accurate estimate of age.
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Problems with Fossils?
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Problems with Fossils?
• Dating is only an approximation
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Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
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Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
• Holes in the fossil record
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Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
• Holes in the fossil record
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Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
• Holes in the fossil record
So what do scientists turn to?
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????
Land Mammal
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????Where are the
Intermediates?
Land Mammal
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????Where are the
Intermediates?
Land Mammal
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????Where are the
Intermediates?
Land Mammal
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Land Mammal
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2006 Fossil Discovery of Early Tetrapod
• Missing link from sea to land animals
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2006 Fossil Discovery of Early Tetrapod
• Missing link from sea to land animals
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Comparative Biochemistry & Cell Biology show that…
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy• Organisms that are related often have
similar types of proteins and antibodies
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy• Organisms that are related often have
similar types of proteins and antibodies
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy• Organisms that are related often have
similar types of proteins and antibodies
![Page 49: 1.2](https://reader033.vdocuments.site/reader033/viewer/2022060108/55508e33b4c905a85c8b4f47/html5/thumbnails/49.jpg)
Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy• Organisms that are related often have
similar types of proteins and antibodies
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Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
• ATP is the universal form of energy• Organisms that are related often have
similar types of proteins and antibodies
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Comparative Embryology
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Comparative Embryology
• Species that are known to be closely related show similar embryonic development.
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Comparative Embryology
• Species that are known to be closely related show similar embryonic development.
• Inference: The longer two embryos stay looking similar, the more closely related they are.
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Comparative Anatomy
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Comparative Anatomy• Study of biological structures in different organisms
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Comparative Anatomy• Study of biological structures in different organisms
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Comparative Anatomy• Study of biological structures in different organisms
• Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
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Comparative Anatomy• Study of biological structures in different organisms
• Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
ex. Pentadactyl limb in mammals
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Comparative Anatomy• Study of biological structures in different organisms
• Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
ex. Pentadactyl limb in mammals• Divergent evolution
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Comparative Anatomy• Study of biological structures in different organisms
• Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
ex. Pentadactyl limb in mammals• Divergent evolution
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Comparative Anatomy• Study of biological structures in different organisms
• Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
ex. Pentadactyl limb in mammals• Divergent evolution
• Analogous structures: Structure of two unrelated species that can evolve to look alike on the basis that they serve a similar function in a similar environment.
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Analogous structures
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Analogous structures
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Analogous structures
• Separate evolution of structures
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Analogous structures
• Separate evolution of structures– similar functions
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Analogous structures
• Separate evolution of structures– similar functions– similar external form
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Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development
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Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin
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Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin– no evolutionary relationship
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Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin– no evolutionary relationship
Solving a similar problem with a similar solution
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Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin– no evolutionary relationship
Solving a similar problem with a similar solution
Don’t be fooledby their looks!
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Vestigial Structures
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Vestigial Structures• Modern animals may have structures that
serve little or no function
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of
walking ancestors
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Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
– evidence of change over time
• some snakes & whales
show remains of the
pelvis & leg bones of
walking ancestors
• human tail bone
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Vestigial Structures• Hind leg bones on whale fossils
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Vestigial Structures• Hind leg bones on whale fossils
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Vestigial Structures• Hind leg bones on whale fossils
Why would whaleshave pelvis & leg bonesif they were always
sea creatures?
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ANY QUESTIONS??
This is the time to ask…