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Evolution
Thomas Malthus (1798)
Human population will grow faster than the
space and food supplies needed to
survive.
Result: Poverty, famine, overcrowding,
disease…
Human Population Growth
Population Growth Chart
Carrying Capacity:
The maximum
number of individuals
in a population that
can be supported by
a particular
environment.
Jean-Baptiste Lamarck -
Inheritance of Acquired Traits (1809)
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Believed that organisms would gain or lose
features if they overused or did not use the
traits
These traits could be passed on to their
offspring
One of the first to propose a mechanism to
explain why organisms change over time
Lamarck’s Hypothesis (1809)

Tendency Toward Perfection
–
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Use and Disuse
–
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organisms are continually changing and acquiring features that
help them live more successfully in their environments
organisms could alter the size or shape of particular organs by
using their bodies in new ways
Inheritance of acquired traits
–
if during its lifetime an animal somehow altered a body
structure, it would pass that change on to its offspring
Lamarck’s Hypothesis (1809)
of
Inheritance of Acquired Traits
Is this idea supported by scientific
evidence?
WRONG!!
WRONG!!
Lamarck’s Hypothesis (1809)
of
Inheritance of Acquired Traits
Is this idea supported by scientific
evidence?
No
Lamarck’s Hypothesis (1809)
Lamarck’s hypothesis of evolution
was incorrect in several ways, but he
was the first to recognize that
organisms are well suited for their
environment – this is a key concept
for future work.
Charles Lyell (1833)
Geological processes occurring now are
the same geological processes that
shaped Earth’s physical features over
long periods of time.
Charles Darwin - 1831

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Charles Darwin sails on the H.M.S. Beagle
Made numerous observations of how
populations differed from island to island of
the Galapagos Islands.
Galapagos Finches
Charles Darwin - 1831

Collected evidence to support a
hypothesis about the way life changes over
time.
Charles Darwin

Darwin took a presented idea and applied it to
plants and animals. Since they have more
offspring than humans, this “Struggle for
Existence” would apply more strongly to plants
and animals. (Malthus)
Charles Darwin - 1831

Darwin realized if the Earth could
change over time, life itself might
change over time in response to
physical changes of the Earth and that
the changes he proposed would
require many, many years. (Lyell’s
work)
The Scientific Theory of Biological
Evolution
1859 - Charles Darwin publishes On the Origin of
Species by Means of Natural Selection.
 Evidence for this hypothesis has since been
described in many diverse studies and is well
supported
 Darwin’s original hypothesis is now known as
the Scientific Theory of Biological Evolution.
These studies include:

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the fossil record
population genetics
animal behavior
DNA fingerprinting
antibiotic resistance in bacteria
How does Natural Selection drive
Evolution?
Different organisms within a species have
differences in morphology and physiology.
Morphology – the form or shape of an
organism.
Different organisms within a species have
differences in morphology and physiology.
Physiology - the
mechanical,
physical,
and biochemical
functions of living
organisms.
2. These differences change the ability of
an organism to survive and reproduce.
An adaptation is any inherited
characteristic that increases
an organism’s chance of
survival and ability to
reproduce.
Example: Monarch butterfly is
poisonous to eat and they
have special coloration to
warn predators
Those individuals that are better able
to survive and reproduce (have
higher fitness for their environment)
pass on their morphological and
physiological differences to their
offspring.
Over time the
population is
changed
based on
selective
pressures of
Selective pressure is any factor that
makes it hard for some organisms
to continue surviving, and rewards
any advantage that some
organisms may have been born
with.
Selective pressures include:
climate changes
food supply changes
predators
sexual selection
What was the selective pressure in
your dot experiment?
Example of selective pressure:
Some antelopes are swift and instinctively run in a zigzag pattern. Some lions are fast and powerful.
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What is the source of variation in antelopes?
What is the selective pressure?
What is the adaptation that made it successful in the
environment?
Activity – Bacteria Resistance
Activity – Bacteria Resistance
1. What was the ultimate source of variation in
the species?
2. What was the selective pressure described?
3. What was the adaptation of the organism that
made it successful in the changed
environment?
4. How did the Mycobacterium tuberculosis
change?
Activity – Galapagos Finches
Thirteen species of finches live on the Galápagos, the famous island
group visited by Charles Darwin in the 1830s. The finches have a
variety of bill shapes and sizes, all suited to their varying diets and
lifestyles. Some birds have beaks better suited for eating cactus;
some have long beaks better suited for eating insects, or short beaks
for eating hard seeds.
A variety of finches ended up on moist, rainy islands in which there was a
shortage of seeds, but many grub-like insects were living under tree
bark. The long-beaked birds could survive on grubs, and would pass
their genetic traits to their offspring. The others would die out. Natural
selection caused the long beaked ‘woodpecker finch’ to survive.
Darwin did not believe that the environment was producing the variation
within the finch populations. He correctly thought that the variation
already existed and that nature just selected for the most suitable beak
shape and against less useful ones.
Activity – Galapagos Finches
1. What was the ultimate source of variation in the
species?
2. What was the selective pressure described?
3. What was the adaptation of the organism that
made it successful in the changed
environment?
4. How did the finch change?
Deer Mice

Deer mice are widespread across North America, but they
usually have dark coat, so that they can blend into dark soils
and stay hidden from owls. However, soil in Nebraska is lightcolored sand. Over a period of several thousand years the deer
mouse in Nebraska evolved a pale coat that helped it to evade
predators. Scientists at Harvard and at the University Of
California at Berkeley discovered a single gene called Agouti in
light colored mice which is expressed in higher amounts and for
longer than the genes that code for dark hair. The gene
emerged about 4,000 years ago, which was only a few
thousand years after the dark coated mice colonized the new
sandy home. Its spread was rapid. Agouti did not occur before
the colonization of the sandy environment, and when it did
appear selection acted on it to confer an advantage, making it
more widespread
Activity – Deer Mice
1. What was the ultimate source of variation in
the deer mice?
2. What was the selective pressure described?
3. What was the adaptation of the organism
that made it successful in the changed
environment?
4. How did the population of deer mice
change?
1.
The term “survival of the fittest” is closely
associated with Charles Darwin’s ideas of
change over time. If an organism is “fit”, it
most likely will –
A. become extinct
B. pass down its genes to an offspring
C. migrate to a new ecosystem
D. change in order to survive
2. Lizards closely resemble the plants and
trees in which they live. This is most likely
because
A. the lizard has learned to change colors.
B. the lizard is smaller than the leaves of the
trees.
C. ancestors of the lizards with the same
traits survived and reproduced.
D. the food eaten by lizards lives in plants.
Peppered Moth Simulation

Read the background information to yourself

View the peppered moth simulation and fill in your
data table.
Click here:
Peppered Moth Simulation
Discussion questions:
1. What differences were present in the moths? What
caused those differences? Where they differences in
morphology or physiology?
2. Before the industrial revolution, which color of
organism had the adaptation that was most fit for the
environment?
3. What type of selective pressures acted on the
moths?
Looking for proof of similar ancestry
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Embryology
Homologous structures
Analogous structures
Vestigial structures
Genetic similarities (DNA)
Looking for proof of Similar Ancestry
Natural selection acts on the populations
separately, which over time, causes the
populations to diverge morphologically and
physiologically.
Organisms that are unrelated
in the same types of
habitats elsewhere in the
world had the same
selective pressures
acting on them, and
therefore, developed the
similar characteristics.
Looking for proof of similar ancestry
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Embryology
Homologous structures
Analogous structures
Vestigial structures
Genetic similarities (DNA)
Embryology
The early stages of vertebrate development are
all very similar.
Vertebrates start to diverge into frog, alligator,
human, and ostrich form in the later stages of
development.
Homologous Body Structures
Structures derived from a
common ancestor or the
same evolutionary or
developmental origin.
Homologous Body Structures
EX. Developmentally, a human
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arm, whale fin, alligator
leg, and bird wing share
the same bones
Due to different selective
pressures and occupying
different niches, these
bones can have
dramatically different
structures.
Analogous Structures
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Structures that seem similar – but they do not
share a recent common ancestor
Similar in function but different in structure and
embryologic origin indicates that the organisms
had different recent ancestors
Evolved separately to perform a similar function
The moth wing is analogous to the a
bird and bat wing.
Vestigial Structures
Structures that have
become reduced in size
because they do not
have a true contributing
function or role in
survival
Dewclaws (E) in most
mammals serve no purpose
and have been reduced in
size
White Board Practice
Homologous, Analogous or Vestigial?
Dolphins (which are mammals)
and fish both have similar body
shapes adapted for moving in
water.
Analogous
Homologous, Analogous or Vestigial?
This species of
cave-dwelling
salamander has
eyebuds, but is
completely
blind.
Vestigial
Homologous, Analogous or Vestigial?
Homologous
Human – 7 neck bones
Giraffe – 7 neck bones
Whale – 7 neck bones
Homologous, Analogous or Vestigial?
The ear muscles, appendix, and
tailbone in humans.
Vestigial
Homologous, Analogous or Vestigial?
Indicates that two organisms
probably have a common ancestor.
Homologous
Homologous,
Analogous or
Vestigial?
Compare the
entire wing.
What about
the yellow
bones?
Within A – Homologous
a
a
Between A & B - Analogous
b
Genetic dataWe used to compare species based solely on
their morphology (present day and fossils)
Now, comparative studies of DNA sequences of
organisms shows how similar DNA is
between some species, and different from
other species
This can confirm what was previously thought,
or it can cause scientists to rethink relations
between organisms.
Below is a short section of DNA:
A C A T A T T A G
What do the A, C, T and G represent?
Now compare the DNA to a close
ancestor:
Living organism:
A C A T A T T A G
Ancestor:
A T A T A T T A C
•On which nucleotide(s) do the sequences
differ?
•What is this difference called?
You try it!
“It’s molecular time” Directions
1.
2.
3.
You have 9 nitrogen base sequences
from a section of DNA similar to what you
might find in a human. Look for the
sequence labeled “living DNA”.
Find the closest ancestor to the living
DNA and place it below the living DNA
Place the rest of the sequences in the
correct order, from present (living) to
oldest ancestor.
It’s Molecular Time Discuss:
What did you use to make your decision?
Were you correct in your order?
What did you use to make your decision?
Were you correct in your order
It’s molecular time
Assume that the rate of mutation is one
mutation for every 10,000 years. How
many years separate the “living DNA” from
its oldest ancestor?
DNA comparisons help us make family trees:
We can also
compare amino
acid sequences by
looking at how
many differences
are there
The table below shows chemicals found in certain bacteria.
Each capital letter represents a different chemical. Which
two bacteria are the most closely related?
Bacteria
Chemicals Present
Bacteria 1
A, G, T, C, L, E, S, H
Bacteria 2
A, G, T, C, L, D
Bacteria 3
A, G, T, C, L, D, P, U, S, R, I, V
Bacteria 4
A, G, T, C, L, D, H
Examining the Fossil Record
Activity
If today’s species came from ancient
species, then we should be able to find
remains of those species that no longer
exist.
Fossils are found all over the world
The Fossil Record
How are fossils formed?
Water carries small rock
particles to lakes and seas.
Dead organisms are buried
by layers of sediment, which
forms new rock.
The preserved remains
may later be discovered
and studied.
The Fossil Record shows
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species that once existed and are now extinct.
transitional forms: fossils or organisms that show
the intermediate states between an ancestral form
and that of its descendants.
Have you noticed that organisms can
be different within the fossil record?
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Gradualism – slight changes
within a population over time
(subtle)
Punctuated equilibrium – a
quick change in a population
(dramatic - indicates a major
event)
Stasis – the idea that during
periods of time, little if any
change is observed within a
population (none)
Fossil Ages
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How can we figure out how old a fossil is?
Relative Dating
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uses the layers of fossils
older fossils are found below more recent ones
living organisms resemble fossils although
differences may be evident
A
B
C
D
What conclusions
and inferences can
you draw from this
figure?
Below is a drawing of the fossils found in a partial
excavation completed by a paleontologist.
Layer A
Layer B
Layer C
Layer D
Layer E
Which layer is the oldest? Which
layer is the youngest?
Oldest = F, Youngest = A
Do the layers support the idea that
change has occurred over a
long period of time?
Yes, water to desert conditions
What might have happened from
layer C to layer B?
erosion
Layer F
Radioactive Dating

using carbon dating on rocks and fossils to
determine a more accurate time frame in
which the organism lived.
 We know how long it
takes for radioactive
carbon to decay. By
identifying how much is
left in a sample, we can
give it an age.
How old is the Earth?
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The fossil record is used to determine the
Earth’s age.
Evidence has been collected and scientists
have created the Geologic Time Scale which
identifies major events in time.
The Earth is estimated to be 4.6 billion years
old
Geologic Time Scale
Era
Cenozoic
Mesozoic
Paleozoic
Precambrian
Time
Period
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Time
(millions of
years ago)
1.8–present
65–1.8
145–65
208–145
245–208
290–245
363–290
410–363
440–410
505–440
544–505
650–544
Key Events
Glaciations; mammals increased; humans
Mammals diversified; grasses
Aquatic reptiles diversified; flowering plants; mass extinction
Dinosaurs diversified; birds
Dinosaurs; small mammals; cone-bearing plants
Reptiles diversified; seed plants; mass extinction
Reptiles; winged insects diversified; coal swamps
Fishes diversified; land vertebrates (primitive amphibians)
Land plants; land animals (arthropods)
Aquatic arthropods; mollusks; vertebrates (jawless fishes)
Marine invertebrates diversified; most animal phyla evolved
Anaerobic, then photosynthetic prokaryotes; eukaryotes,
then multicellular life
Biogeography
Geographic distribution of living organisms
Fossils are found all over the world
The geographic
location of
fossils show
where extinct
organisms
used to thrive
Plate Tectonics
Shows how the
continents fit like
pieces of a
puzzle.
Explains how the
distribution of
fossils can be
global.
Now that the continents have
separated…
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Are changes still occurring within
populations?
–
What do you think?
Case Study: Galapagos Islands
Each island in the Galapagos had
similar organisms but were
different enough to be different
species.
Could they have changed over time
from a common ancestor from the
mainland?
Galapagos Islands
Each island habitat has different selective
pressures acting on the organisms.
A scientist finds fossils of pine branches,
birds, and deer-like animals. This area
was at one time most likely a –
A. forest
B. ocean
C. desert
D. tropical rain forest
In-Class Activity – Geologic Time Scale

Answer the Questions relating to the
Geologic Time Scale
Practice Question
An early discovery relating to pesticide use,
is that insects may eventually evolve to
become resistant to chemicals. When
sprayed with pesticides, many insects will
initially be very susceptible. After repeated
applications of the pesticide, it is less
effective.
Explain what happened in terms of natural
Summary of Darwin’s Theory:
1.
Individual organisms of a population differ
and much of this variation is heritable.
2.
Organisms produce more offspring than
can possibly survive and those that do not
survive do not reproduce.
Summary of Darwin’s Theory:
3.
Each unique organism has different
advantages and disadvantages in the
struggle for existence. Individuals best
suited to their environment survive and
reproduce most successfully. They pass on
their adaptations to their offspring.
This process changes species over time in
response to selective pressures.
Summary of Darwin’s Theory:
4.
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Species alive today are
descended with modification
from ancestral species that
lived in the distant past.
This process by which
diverse species evolved from
common ancestors unites all
organisms on Earth into a
single tree of life.
Practice Question
The fact that all organisms use DNA for their
genetic material is evidence that all
organisms —
A. have been genetically engineered
B. evolve at the same rate
C. share a common ancestor
D. undergo sexual reproduction
What evidence do we have that
supports the Theory of Evolution?
Exit Ticket – Jan. 25 Complete the
graphic organizer
1. Fossil
Record
Evidence
of
Evolution
5. Genetic
Data
2. Biogeography
3. Embryology
4. Homologous
Structures
Practice Question
Which of the following statements does not support
the theory of change over time?
A. the fossil record shows a history of organisms
B. animals can cause traits to change
C. DNA sequences show the relatedness of
organisms
D. organisms have adaptations which increase
survival
What does it mean
when a nonscientist says
“It’s just a theory”?

In non-scientific terms, if something is said to
be “just a theory,” it usually means that it is a
mere guess, or is unproven.
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In science, the word theory has a different
meaning
A Scientific Theory is
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a well-tested explanation
based on a broad range of observations and
data
accepted to be true by the scientific
community as a whole
tested repeatedly by new data
not absolute – can be tweaked, but seldom
entirely replaced
A Hypothesis is
formulated from observations and is tested
scientifically to develop supporting evidence.
Until sufficient supporting evidence is found,
a hypothesis may be disputed by science.
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Scientists make observations, develop
hypotheses and collect data that either
support or refute their hypotheses.
Data collected showed that populations
changed over time (think of your dot
experiment).
Scientists developed hypotheses to explain
these changes in populations.
You try it! Complete “Truth or
Misconception” in your notes
Complete Evidence of Evolution WS