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Do Now
1. What about the skeleton in
the photo reminds you of a
living thing?
2. What about the skeleton
reminds you of a nonliving
3. What might studying this
skeleton help you to learn
about living things?
4. What might be some
benefits of studying living
Chapters 14 & 15
1/2. The skeleton is made of organic materials and was
once part of a living thing, but the skeleton cannot move
on its own, reproduce, or grow.
3. Studying the skeleton could reveal how the internal
structure of a living thing is supported, how bones are
formed, or how living things grow.
4. The study of living things can help people to understand
themselves and might lead to practical benefits such as
cures for disease, improvements to the environment, and
more efficient use of Earth’s resources.
To understand what evolution is.
To explain spontaneous generation, theory
of biogenesis and the primordial soup
What is Evolution?
The change in living organisms over time!
The Origin of Life: Early Ideas
Where do living things come from??
Spontaneous Generation:
◦ The idea that life arises from non-life
 Ex: mud gives rise to worms?? We can make mice out of hay??
Fransisco Redi:
◦ An Italian scientist
◦ Tested the idea of spontaneous generation.
What happens when you leave meat
out for a long time?
Redi’s Experiment- 1668
He placed meat in both an open container,
and a closed container to see what
Redi’s Conclusions
Maggots come from
FLIES, not meat.
Life must come from
life, not spontaneous
generation right?
◦ Not completely rejected
until later on…
Now what?
Louis Pasteur
experimented with the
“Theory of biogenesis”.
Theory of
◦ Only living organisms can
produce other living
Pasteur’s Experiment
Tested the idea of spontaneous generation
 Nutrient rich broth was exposed to air but
not dust and spores
Pasteur’s Conclusion
Living organisms must be
able to enter the broth in
order to grow
Living things do NOT
spontaneously generate
What about LIFE?
So we know that life can only come from life… but
where did the original life come from???
What was in the Earth’s atmosphere??
Gases were expelled
from volcanoes
◦ Water Vapor (H2O)
◦ Carbon Dioxide (CO2)
◦ Sulfur Dioxide (SO2)
◦ Carbon Monoxide (CO)
◦ Hydrogen Sulfide (H2S)
◦ Hydrogen Cyanide (HCN)
◦ Nitrogen (N2)
◦ Hydrogen (H2)
◦ NO OXYGEN!!!!!!!
How do we KNOW that was what the
atmosphere was made of?
Miller and Urey!
◦ Created an experiment to show how the first molecules of life
could be formed…
◦ Water + hypothesized gases + electric discharges
(methane, amonia,
(energy: like lightning)
Amino acids & other organic compounds!
Miller and Urey’s Conclusions
Primordial soup
◦ early hypothesis about the
origin of life
◦ simple organic molecules could
be made from inorganic
Primary Energy
◦ UV light from the Sun
◦ Electric discharge in lightning
Overview of Evolution…
Cellular Evolution
Scientists hypothesize that the first cells were
Modern prokaryotes called archaea are the closest
relatives of Earth’s first cells.
Archaea are autotrophic
They do not obtain their energy from the Sun.
Photosynthesizing Prokaryotes
prokaryotes evolved
not long after the
Prokaryotes, called
cyanobacteria, have
been found in rocks as
old as 3.5 billion years.
Conclusion Activity
State the scientist who came up with different theories:
1. Discovered part of cell theory.
2. Created early earth environment to test hypothesis.
3. First to discover that spontaneous generation was false
4. Worked with maggots and meat
5. Discovered primordial soup hypothesis.
Do Now
Who were the 3 scientists we talked about
and what did each of them do?
Determine how cells developed.
 Explain the endosymbiont theory.
 List and describe the steps of natural
Think back…
How are prokaryotes and eukaryotes different?
How did we get Eukaryotes?
“Endosymbiont Theory”
Eukaryotic cells lived in association with prokaryotic
Relationship between the cells became mutually
beneficial, and the prokaryotic symbionts became
organelles inside eukaryotic cells
This theory explains the origin of chloroplasts and
Endosymbiont Theory
Evidence of Endosymbiosis
Mitochondria have circular DNA like bacteria
Replicates like bacteria separate from the host cell
DNA codes for proteins that are similar to bacterial proteins
Mitochondria make their own proteins
Mitochondria have two membranes (one from the host cell
and one from their own cell membrane)
Fast forward a couple billion years…
Who is this guy?
Charles Darwin
Darwin was a Naturalist
He collect biological and geological specimens during
his travels on his ship the HMS Beagle.
Darwin and the Galapagos Islands
Darwin collected different birds on each of the 4 islands
he went to. (mostly finches)
discovered that each island had their own, slightly different
varieties of birds.
Populations from the mainland changed after reaching the
Darwin hypothesized that new species could
appear gradually through small changes
So What?
Darwin Concluded…
 Humans could change
species by artificial
selection, then the same
process could work in
Ex) Corn Selection
Other examples of “artificial selection”
Artificial selection◼ Artificial
selection or selective breeding occurs
when humans breed other animals and plants for
specific and desired traits (examples: Dogs,
horses, vegetables).
◼ However,
organisms have been changing for
millions of years.
Artificial selection
◼ Humans have been
manipulating other
animals and plants
for many years.
◼ Think of different
breeds of dogs:
Pitbulls, Rottweiler,
Bulldogs, Labrador
Natural Selection
Some competitors in the struggle for
existence are better equipped for survival
than others; those less equipped die.
Natural Selection
1) Individuals in a population show variations
due to genetic variation.
Genetic variation = differences in DNA and
Natural Selection
2) Variations can be inherited.
◦ Organisms that survive and reproduce pass on the
genes for their adaptations.
Natural Selection
3) Organisms have more offspring than can survive
on available resources.
◦ Not all organisms in a population can survive. Organisms
with adaptations to their environment are most likely to
survive and reproduce.
Review: What are adaptations?
Natural Selection
4) Variations that increase reproductive success will
have a greater chance of being passed on.
◦ Evolution also occurs through sexual selection in which
members of the same species must compete for a mate to
pass on their genes.
◦ Eventually all organisms in the population inherit the genes
and express the adaptation.
Real World Examples
African elephants typically have large tusks. The ivory in the tusks is
highly valued by some people, so hunters have hunted and killed
elephants to tear out their tusks and sell them (usually illegally) for
decades. Some African elephants have a rare trait -- they never
develop tusks at all. In 1930, about 1 percent of all elephants had no
tusks. The ivory hunters didn't bother killing them because there was
no ivory to recover. Meanwhile, elephants with tusks were killed off by
the hundreds, many of them before they ever had a chance to
◼The result: As many as 38 percent of the
elephants in some modern populations
have no tusks [source: BBC News].
◼Unfortunately, this isn't really a happy
ending for the elephants, since their tusks
are used for digging and defense.
Example: Insects
◼ Pesticides
are chemicals used to kill
insects that eat crops. Most insects are
not pesticide-resistant (protected), but
some insects are pesticide-resistant
◼ What
is the cause of these differences??
▪ Genetic variation! (different genes)
Example: Insects
◼ When
farmers spray pesticides on
their crops, most of the insects that
eat the crops will not survive.
◼ What trait would be an
◼ Pesticide-resistance
◼ Which
insects will NOT survive?
Example: Insects
◼ What
do the organisms with the adaptation
◼ Insects with pesticide resistance reproduce
and pass on genes for pesticide-resistance
to their offspring
◼ What
happens to the rest of those without
the adaptation?
◼ More of the insects without pesticide
resistance die as farmers continue to spray
the crops
Example: Insects
◼ Eventually what happens?
◼ What trait do all of the surviving insects have?
▪ All surviving insects are pesticide-resistant
◼ How did the population evolve?
▪ From being mostly not pesticide-resistant to being all
pesticide resistant
◼ What is this process called?
▪ Natural selection!
◼ What problems might this cause for farmers?
Example: Bird Beaks
◼ Most
birds on an island have fragile, thin
beaks and a few have strong, thick beaks.
◼ What
is the cause of these differences??
▪ Genetic variation!
Use the following example and explain
the four parts of natural selection.
A male peacock has bright colored feathers to
attract a mate
◦ 1.Variation
◦ 2. Inherited
◦ 3. More offspring are produced than can survive
◦ 4.Varations with Reproductive Success
Go through the 4 steps of natural selection with
these moths…
1. What did Darwin infer A. Animal breeders could create new species.
from his observations of B. A similar process could work in nature.
artificial selection?
C. Reproductive success could be increased.
D. Variation in a species could be produced.
2. What is the
relationship between
natural selection and
A. They mean the same thing.
B. Evolution works against natural selection.
C. Evolution explains how natural selection works.
D. Natural selection explains how evolution works.
3. Which explains why the
A. The different tortoises were different species.
B. The environment on each island was different.
C. Each type of tortoise could survive only on its own
D. They arrived on the islands from different continents.
tortoises on the different
islands of the Galápagos
had slightly different
variations in their shells?
Think – Pair - Share
Brainstorm- How do scientists know that
evolution occurred?
What is some evidence for evolution?
15.2 Evidence for Evolution
1. Fossil Evidence
2. Evidence from Anatomy
3. Embryology
4. Biochemistry
◦ Genetic Evidence
5. Geographic Distribution
6. Direct Observation
1. Fossil Evidence
Fossils provide a record of species that lived long
Fossils show that ancient species share similarities
with species that now live on Earth.
2. Evidence from Anatomy
A. Homologous Parts
 Anatomically similar structures inherited from a
common ancestor are called homologous
2. Evidence from Anatomy
B.Vestigial Structures
 Structures that are the reduced forms of functional structures in other
 Evolutionary theory predicts that these features will become smaller
over time until they are lost.
2. Evidence from Anatomy
D. Analogous Structures:
◦ Can be used for the same purpose (look similar),
but not inherited from a recent common ancestor
◦ Ex. Wings of an eagle and beetle
Think – Pair - Share
Compare and contrast analogous and homologous
List 3 examples of each not mentioned in class.
3. Embryology
Vertebrate embryos exhibit homologous structures
during certain phases of development
Become totally different structures in the adult
Which one is human?
Fish Salamander Tortoise
What Species is it?
Do Now
What are homologous structures? Give
an example
What are analogous structures? Give an
What are vestigial structures? Give an
4. Biochemistry
Common ancestry can be seen in the complex
metabolic molecules that many different organisms
◦ Ex. Hemoglobin, amino acids
4. Biochemistry – Genetic Evidence
Mutations are the raw
material for evolutionary
Genetics can tell us how
different groups of
organisms are related back
through time.
5. Geographic Distribution
The distribution of plants and animals that Darwin saw
first suggested evolution to Darwin.
Ex. Animals on S. America mainland were more similar to
other S. American animals than to animals living in
comparable environments in Europe
6. Direct Observations
Some evolution takes place more rapidly than others
Ex. evolution of drug resistant bacteria. This type of
evolution can be directly observed by scientists.
Conclusion Activity
Match the following with the type of evidence
1. The HIV virus is constantly
changing and evolving.
A. Fossil Evidence
2. All living things share the same
amino acids
B. Biochemical Evidence
3. Evidence that Dinosaurs were
once on earth
C. Embryology
4. Humans and Chimps have
similar bone structures
D. Direct Observation
5. The fetus of a pig and dog go
through similar developments
E. Evidence from Anatomy
Do Now
What is an adaptation?
Explain how adaptations are shaped by
natural selection.
A trait shaped by natural selection that increases an
organism’s reproductive success
◦ How well an organism is suited for an environment
◦ How well an organism can pass it’s traits to the next generation
Types of Adaptation
◦ Allows an organism to become almost invisible to
One species evolves to resemble another
Western coral snake
California kingsnake
A species is a group of organisms that can interbreed and
produce fertile offspring in nature.
interspecies breeding can sometimes produce offspring that are
infertile such as horses and donkeys producing mules
Speciation: the development of a new species.
Work on the worksheet as a review of
the evidence of evolution.
15.3 Types of Natural Selection
Stabilizing Selection
◦ Eliminates extreme
expressions of a trait because
the average expression
increases survival
 Ex: most human babies are born
with average weights
Directional Selection
This happens when an extreme version of a trait
makes an organism more fit.
◦ Ex: when something happens to change the environment of
an organism such as a drought.
Disruptive Selection
A process that splits a population into two
groups because the organisms that express
extreme traits survive and the average trait
does not.
◦ Ex: Snake coloration
Sexual Selection
Frequency of a trait is based on the ability to
attract a mate.
Males evolve with threatening characteristics or
bright colors to attract females.
Sexual Selection
Peacock Video
Get with a partner!
Types of Natural Selection worksheet
Patterns of Evolution
1. Divergent Evolution
- Adaptive radiation
- Reproductive Isolation
2. Convergent Evolution
3. Coevolution
1. Divergent Evolution
When one species evolves into two or more
species with different characteristics
◦ One type of Divergent evolution is called adaptive
1. Divergent Evolution (cont.)
Adaptive Radiation:
◦ Can occur in a relatively short time
◦ One species gives rise to many different species in
response to the creation of new habitat or some
other ecological opportunity
1. Divergent Evolution (cont.)
Divergent evolution can sometimes lead to reproductive
Prevents two species from mating
It can be caused by:
◦ 1. geographic isolation (allopatric speciation)
◦ 2. genetic mutations (sympatric speciation)
 Polyploidy:
Types of Speciation
Allopatric◦ A physical barrier divides one population into two or more
populations. Over time each species evolves and can no longer
 Ex: grand canyon produced barrier that separated squirrels
Sympatric◦ A new species evolves without a physical barrier.
 Ex: many insect species and plants (polyploidy is a mutation where plants
can no longer interbreed with the normal population)
2. Convergent Evolution
Unrelated species evolve similar traits even though they are not
closely related.
These traits are often structurally very different.
Bird Wing
Bat Wing
Analogous Structures
Result from Convergent Evolution
Squid Eye
Human Eye
3. Coevolution
The relationship between two species might be so close that
the evolution of one species affects the evolution of the other
Coevolutionary arms race
Orchid Fly
Garter snake consumes a poisonous newt
Label the following:
Do Now
Explain the difference between divergent
and convergent evolution
Explain the differences between:
◦ Homologous and analogous structures
◦ Convergent and divergent evolution
Tempo of Speciation
◦ Evolution proceeds in small, gradual steps according
to a theory called gradualism.
Punctuated Equilibrium:
◦ Punctuated equilibrium explains rapid spurts of
genetic change causing species to diverge quickly.
What do you think?
What tempo of evolution does this model
A. gradual
B. elevated
C. sequential
D. punctuated
Do Now
How did humans evolve?
Primate Evolution
16.2 Hominoids to Hominins
 The lineage that most likely led to humans
split off from the other African apes
sometime between 8 and 5 mya.
 Hominins have bigger brains.
 Thinner and flatter face
 Smaller teeth
 High manual dexterity
 Bipedal
Human Evolution Ch. 16
Primate adaptations
high level of problem solving ability
large brain size when compared to body weight
flexible shoulders
flexible hand with an opposable thumb
African Origins
Human Evolution
Conclusion Activity
Compare and Contrast Apes and Humans