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Post on 11-May-2015
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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?
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
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
But the fossil record shows…
Descent with Modification
Darwin’s idea that each species living today arose from a pre-existing
species!
Hundreds of millions of years passed before atmospheric oxygen levels were high enough to support eukaryotes.
Evidence Supporting Evolution
Evidence Supporting Evolution
• Fossils (descent with modification)
Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry
Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology
Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology• Comparative embryology
Evidence Supporting Evolution
• Fossils (descent with modification)
• Comparative biochemistry• Comparative cell biology• Comparative embryology
• Comparative anatomy
Fossils as Evidence
Fossils as Evidence
• A fossil is the remains of organisms that lived in the past.
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.)
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
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?
How old are fossils?
How old are fossils?
• Relative dating: Fossils can be dated in correlation with the age of the strata (layer of rock) they are in.
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.
Problems with Fossils?
Problems with Fossils?
• Dating is only an approximation
Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
• Holes in the fossil record
Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied organisms
• Holes in the fossil record
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?
????
Land Mammal
????Where are the
Intermediates?
Land Mammal
????Where are the
Intermediates?
Land Mammal
????Where are the
Intermediates?
Land Mammal
Land Mammal
2006 Fossil Discovery of Early Tetrapod
• Missing link from sea to land animals
2006 Fossil Discovery of Early Tetrapod
• Missing link from sea to land animals
Comparative Biochemistry & Cell Biology show that…
Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
Comparative Biochemistry & Cell Biology show that…
• the genetic code in nucleic acids is almost universal
• physiological processes follow common metabolic pathways
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
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
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
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
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
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
Comparative Embryology
Comparative Embryology
• Species that are known to be closely related show similar embryonic development.
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.
Comparative Anatomy
Comparative Anatomy• Study of biological structures in different organisms
Comparative Anatomy• Study of biological structures in different organisms
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.
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
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
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
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.
Analogous structures
Analogous structures
Analogous structures
• Separate evolution of structures
Analogous structures
• Separate evolution of structures– similar functions
Analogous structures
• Separate evolution of structures– similar functions– similar external form
Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development
Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin
Analogous structures
• Separate evolution of structures– similar functions– similar external form– different internal structure & development– different origin– no evolutionary relationship
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
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!
Vestigial Structures
Vestigial Structures• Modern animals may have structures that
serve little or no function
Vestigial Structures• Modern animals may have structures that
serve little or no function– remnants of structures that were functional in
ancestral species
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
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
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
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
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
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
Vestigial Structures• Hind leg bones on whale fossils
Vestigial Structures• Hind leg bones on whale fossils
Vestigial Structures• Hind leg bones on whale fossils
Why would whaleshave pelvis & leg bonesif they were always
sea creatures?
ANY QUESTIONS??
This is the time to ask…
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