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Evidence for
Evolution
by
Natural Selection
AP Biology
Raven Chapters 1 & 22
2006-2007
Science happens within a culture
What was
the doctrine
of the time?
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TINTORETTO
The Creation of the Animals 1550
Then along comes Darwin…
1831-1836
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22 years old!
Then along comes Darwin…
& those dang finches!
Descendant
species
Warbler finch
Cactus finch
Ancestral
Woodpecker finch
species
Sharp-beaked finch
Small ground
finch
Small insectivorous
tree finch
Large
insectivorous
tree finch
Cactus
eater
Medium
ground finch
Insect eaters
Seed eaters
Vegetarian
tree
finch
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Biology
Bud eater
Large
ground finch
Darwin’’s finches
Differences in
beaks allowed
some finches to…
successfully
compete
successfully feed
successfully
reproduce
pass successful
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traits onto their
offspring
In historical context
Other people’’s ideas paved the
path for Darwin’’s thinking
competition:
struggle for survival
population growth
exceeds food supply
land masses change over
immeasurable time
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Voyage: 1831-1836
November 24, 1859, Darwin published
“On the Origin of Species by Means of Natural Selection””
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Correlation of species to food source
Seed
eaters
Flower
eaters
Insect
eaters
Rapid speciation:
new species filling niches,
because they inherited
successful adaptations.
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Adaptive
Beak variation in Galapagos finches
(a) Cactus eater. The long,
sharp beak of the cactus
ground finch (Geospiza
scandens) helps it tear
and eat cactus flowers
and pulp.
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(c) Seed eater. The large ground
finch (Geospiza magnirostris)
has a large beak adapted for
cracking seeds that fall from
plants to the ground.
(b) Insect eater. The green warbler
finch (Certhidea olivacea) uses its
narrow, pointed beak to grasp insects.
Glyptodont fossils
Sloth fossils
Modern sloth
Modern armadillos
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Why should extinct
species & living species
be found on the
same continent?
Essence of Darwin’’s ideas
Natural selection
heritable variation exists in populations
over-production of offspring
more offspring than the environment can support
competition
for food, mates, nesting sites, escape predators
differential survival
successful traits = adaptations
differential reproduction
adaptations become more
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common in population
Where does Variation come from?
Mutation
random changes to DNA
errors in mitosis & meiosis
environmental damage
Sexual reproduction
mixing of alleles
genetic recombination
new arrangements of alleles in every offspring
new combinations = new phenotypes
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LaMarckian vs. Darwinian view
LaMarck
in reaching higher
vegetation giraffes
stretch their necks &
transmits the acquired
longer neck to offspring
Darwin
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giraffes born with longer
necks survive better &
leave more offspring who
inherit their long necks
Big Idea 1
The process of evolution drives the
diversity and unity of life
cells
DNA
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What are the 4 lines of evidence that
support Darwin’’s ideas?…
Human Macaque Dog Bird
8
32 45
Frog
Lamprey
67
125
0 10 20 30 40 50 60 70 80 90 100 110 120
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1. What are the lines of evidence that support Darwin’’s ideas?
Fossil record
550
500
Body size (kg)
450
Equus
400
350
300
250
Merychippus
200
150
Mesohippus
Hyracotherium
100
50
Nannippus
60 55 50 45 40 35 30 25 20 15 10 5
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Millions of years ago
0
Evolution of birds
Archaeopteryx
lived about 150 mya
links reptiles & birds
Smithsonian Museum,
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Washington,
DC
Evolution of land animals
2006 Fossil Discovery of Early Tetrapod
“Tiktaalik””
“missing link”
” from sea to land animals
from swimming (0 legs) to walking (4 legs)
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Evolution of
marine mammals
Land Mammal
?
?
?
?
But then,
they actually
found my fossil!
At first,
I was just
a joke
!
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Biology
Aquatic Mammal
2. What are the lines of evidence that support Darwin’’s ideas?
Terminal
bud
Lateral
buds
Cabbage
Artificial selection
Brussels
sprouts
Leaves
Flower cluster
Kale
Cauliflower
Stem
Flower
and
stems
Broccoli
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Wild mustard
Kohlrabi
Selective
breeding
the raw genetic
material (variation)
is hidden there
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Natural selection
in action
Resistance…
NOT immunity!
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MRSA
3. What are the lines of evidence that support Darwin’’s ideas?
Anatomical evidence
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Homologous structures
spines
leaves
succulent leaves
Don’’t forget
our plant friends!
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needles
colored leaves
tendrils
Analogous structures
Convergent
Don’
’t be fooled
by evolution
their looks!
Those
tails
Does fins
this &
mean
& sleek
they bodies
have a are
recent
common
ancestor?
analogous
structures
!
Solving a similar problem with a similar solution
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Convergent evolution
marsupial
mammals
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These animals
look very similar but does
that mean they have a
recent common ancestor?
What is this
evidence of?
placental
mammals
Parallel/convergent evolution
Niche
Burrower
Placental Mammals
Mole
Australian Marsupials
Convergent evolution
of analogous
Marsupial mole
burrowing characteristics
Anteater
Anteater
Nocturnal
insectivore
Mouse
Climber
Numbat
Marsupial mouse
Spotted cuscus
Lemur
Glider
Stalking
predator
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Chasing
predator
Flying
squirrel
Sugar glider
Ocelot
Tasmanian cat
Wolf
Tasmanian “wolf””
Vestigial organs
These are
Why would whales
remnants of
have pelvis & leg bones
structures that were
if they were always
functional in
sea creatures?
ancestral species
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4. What are the lines of evidence that support Darwin’’s ideas?
Human
Macaque
Dog Bird
Frog
Lamprey
The sequence in
DNA
proteins
Why &compare
is a &molecular
DNA
proteins
record
of evolutionary
across
species?
relationships.
Comparative hemoglobin structure
8
32
45
67
125
Why compare
these genes?
0
10 20 30 40 50 60 70 80 90 100 110 120
compare common genes
Number of amino acid differencesbetween
hemoglobin (146 aa) of vertebrate species and that
of humans C (respiration)
cytochrome
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hemoglobin (gas exchange)
Building “family”” trees
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Genome sequencing
What can data from whole
genome sequencing tell us
about evolution of humans?
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Primate Common Ancestry?
Chromosome Number in
the Great Apes
(Hominidae)
orangutan (Pogo)
gorilla (Gorilla)
chimpanzee (Pan)
human (Homo)
48
48
48
46
Could we have
just lost a pair of
chromosomes?
Hypothesis:
Change in chromosome number?
If these organisms share a common
ancestor, then is there evidence in
the genome for this change in
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chromosome
number
Chromosomal fusion
Testable prediction:
If common ancestor had 48 chromosomes (24 pairs),
then humans carry a fused chromosome (23 pairs).
What we should find:
Ancestral
Chromosomes Fusion
Chromosome Number in
the Great Apes
(Hominidae)
orangutan (Pogo)
48
gorilla (Gorilla)
48
Testable!48
chimpanzee (Pan)
This is what makes
human (Homo)
46
evolution science
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& not belief!
Homo sapiens
Inactivated
centromere
Telomere
sequences
in middle of
chromosome
Centromere: bonding point between
chromosomes
Telomere: at ends of chromosomes
Hillier et al (2005) “Generation and Annotation of the DNA
sequences of human chromosomes 2 and 4,” Nature 434: 724 – 731.
Guess
what
we
found?!?
Ancestral
Chromosome 2 in
Chromosomes Fusion Homo sapiens
“Chromosome 2 is unique to the human
lineage of evolution, having emerged as a
result of head-to-head fusion of two
chromosomes that remained separate in
Inactivated
other primates. The precise fusion site has
centromere
been located in 2q13–2q14.1, where our
analysis confirmed the presence of multiple
Telomere
subtelomeric duplications to chromosomes 1,
sequences
in middle of
5, 8, 9, 10, 12, 19, 21 and 22. During the
chromosome formation of human chromosome 2, one of
the two centromeres became inactivated
(2q21, which
corresponds
to the centromere
Well
I’ll
from chimp chromosome 13) and the
be a monkey’s
centromeric structure quickly deterioriated.”
…or an ape’s…
uncle!
Human Chromosome #2 shows the exact
point
at which this fusion took place
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"Nothing in biology
makes sense except in
the light of evolution."
-- Theodosius Dobzhansky
March 1973
Geneticist, Columbia University
(1900-1975)
AP Biology
2006-2007
Evolution is "so overwhelmingly
established that it has become
irrational to call it a theory."
-- Ernst Mayr
What Evolution Is
2001
Professor Emeritus, Evolutionary Biology
Harvard University
(1904-2005)
AP Biology
2006-2007
Don’t be a Dodo…
Ask Questions!!
AP Biology
2006-2007