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Division Ave. High School
Ms. Foglia
AP Biology
Evidence supporting evolution
Fossil record
Evidence of Evolution
by Natural Selection
transition species
Anatomical record
homologous & vestigial structures
embryology & development
Molecular record
protein & DNA sequence
Artificial selection
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2007-2008
Dodo bird
Fossil record
human-caused evolution
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Fossil Record
Layers of sedimentary rock contain fossils
new layers cover older ones, creating a
record over time
fossils within layers show that a
succession of organisms have populated
Earth throughout a long period of time
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Fossil record
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Evolutionary change in horses
A record showing us that today’s organisms
550
descended from ancestral species
500
Body size (kg)
450
Equus
400
350
300
250
Merychippus
200
150
Mesohippus
Hyracotherium
100
50
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Nannippus
60 55 50 45 40 35 30 25 20 15 10 5 0
Millions of years ago
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Division Ave. High School
Ms. Foglia
AP Biology
Evolution of birds
Archaeopteryx
Land Mammal
?
lived about 150 mya
links reptiles & birds
?
?
?
Smithsonian Museum,
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Washington, DC
2006 Fossil Discovery of Early Tetrapod
Tiktaalik
“missing link” from sea to land animals
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Anatomical record
Homologous structures
similarities in characteristics resulting
from common ancestry
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Homologous structures
Similar structure
Similar development
Different functions
Evidence of close
evolutionary relationship
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recent common ancestor
Homologous structures
leaves
succulent leaves
needles
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spines
tendrils
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colored leaves
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Division Ave. High School
Ms. Foglia
AP Biology
Analogous structures
Convergent evolution
Flight evolved in 3 separate animal groups
Separate evolution of structures
similar functions
similar external form
different internal structure &
development
different origin
no evolutionary relationship
evolved similar “solution” to similar “problems”
analogous structures
Does this mean
they have a
recent common
ancestor?
Don’t be fooled
by their looks!
Solving a similar problem with a similar solution
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Convergent evolution
Fish: aquatic vertebrates
Dolphins: aquatic mammals
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Parallel Evolution
Convergent evolution in common niches
similar adaptations to
life in the sea
not closely related
filling similar ecological roles in similar
environments, so similar adaptations were selected
but are not closely related
marsupial
mammals
placental
mammals
Those fins & tails
& sleek bodies are
analogous structures!
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Parallel types across continents
Niche
Burrower
Placental Mammals
Mole
Vestigial organs
Modern animals may have structures that
Australian Marsupials
Marsupial mole
serve little or no function
Anteater
Anteater
Nocturnal
insectivore
Numbat
Mouse
Climber
Marsupial mouse
snakes & whales — remains of pelvis & leg bones of
walking ancestors
Spotted cuscus
Lemur
Glider
Stalking
predator
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Chasing
predator
Flying
squirrel
Ocelot
Wolf
remnants of structures that were functional in
ancestral species
deleterious mutations accumulate in genes for
non-critical structures without reducing fitness
eyes on blind cave fish
Sugar glider
human tail bone
Tasmanian cat
Tasmanian “wolf”
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This is not
LaMarck’s loss
from “disuse”!
3
Division Ave. High School
Ms. Foglia
AP Biology
Vestigial organs
Hind leg bones on whale fossils
Comparative embryology
Similar embryological development in
closely related species
Why would whales
have pelvis & leg bones
if they were always
sea creatures?
gill pouch in fish, frog, snake, birds, human, etc.
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Comparative hemoglobin structure
Molecular record
Comparing DNA & protein structure
universal genetic code!
Human Macaque
Why compare
these genes?
DNA & RNA
all vertebrate embryos have similar
structures at different stages of
development
compare common genes
cytochrome C (respiration)
hemoglobin (gas exchange)
Human/kangaroo
DNA & proteins are a molecular
record of evolutionary relationships
Nucleotide substitutions
100
Closely related species have
sequences that are more similar
than distantly related species
Dog/
cow
75
Human/
cow
8
0
25
32 45
67
125
Human/rodent
Pig/
cow
0 10 20 30 40 50 60 70 80 90 100 110 120
Goat/cow
0
Lamprey
Horse/cow
Sheep/
goat
25
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Llama/
cow
Frog
Why does comparing
amino acid sequence
measure evolutionary
relationships?
Rabbit/
rodent
50 Horse/
donkey
Dog Bird
50
75
100
Millions of years ago
125
Building “family” trees
Closely related species (branches) share same line of
descent until their divergence from a common
ancestor
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Number of amino acid differences between
hemoglobin (146 aa) of vertebrate species and that of humans
Artificial selection
Artificial breeding can use variations in
populations to create vastly different
“breeds” & “varieties”
“descendants” of wild mustard
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“descendants” of the wolf
4
Division Ave. High School
Ms. Foglia
AP Biology
Natural selection in action
Insecticide &
drug resistance
insecticide didn’t
kill all individuals
resistant survivors
reproduce
resistance is inherited
insecticide becomes
less & less effective
"Nothing in biology
makes sense except in
the light of evolution."
-- Theodosius Dobzhansky
March 1973
Geneticist, Columbia University
(1900-1975)
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2007-2008
Don’t be a Dodo…
Evolution is "so overwhelmingly
established that it has become
irrational to call it a theory."
Ask Questions!!
-- Ernst Mayr
What Evolution Is
2001
Professor Emeritus, Evolutionary Biology
Harvard University
(1904-2005)
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2007-2008
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