1. AIM:
How can we know that evolution has
actually occurred?
Warm – up:
How does Darwin explain the
presence of organisms alive
today?
2. LaMarck
• Organisms adapted to their environments
ØThrough acquired traits
ØChange 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
3. LaMarck
• Organisms adapted to their environments
ØThrough acquired traits
ØChange 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
19. 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.)
20. 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
21. 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?
24. How old are fossils?
• Relative dating: Fossils can be dated in
correlation with the age of the strata (layer
of rock) they are in.
25. 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.
30. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
31. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
• Holes in the fossil record
32. Problems with Fossils?
• Dating is only an approximation
• No fossils of early or soft-bodied
organisms
• Holes in the fossil record
33. 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?
43. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
44. Comparative Biochemistry &
Cell Biology show that…
• the genetic code in nucleic acids is almost
universal
• physiological processes follow common
metabolic pathways
45. 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
46. 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
47. 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
48. 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
49. 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
50. 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
54. 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.
60. 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.
61. 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
62. 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
63. 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
64. 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.
71. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
72. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
73. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
– no evolutionary relationship
74. 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
75. Analogous structures
• Separate evolution of structures
– similar functions
– similar external form
– different internal structure & development
– different origin
– no evolutionary relationship
Don’t be fooled
by their looks!
Solving a similar problem with a similar solution
78. Vestigial Structures
• Modern animals may have structures that
serve little or no function
– remnants of structures that were functional in
ancestral species
79. 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
80. 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
81. 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
82. 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
83. 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
84. 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