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Chapter 8
Where Did We Come From?
The Evidence for Evolution
Fourth Edition
BIOLOGY
Science for Life | with Physiology
Colleen Belk • Virginia Borden Maier
© 2013 Pearson Education, Inc.
Copyright © 2009 Pearson Education, Inc.
PowerPoint Lecture prepared by
Jill Feinstein
Richland Community College
1 What is Evolution? – The Process of Evolution
 Biological populations
 Groups of individuals of the same species that are
subdivided from other populations by geography
 Biological evolution
 Change in the characteristics of a population of
organisms that occurs of over the course of
generations.
 Evolutionary changes are inherited via genes.
 Other changes may take place because of
environmental changes and are not necessarily
evolutionary.
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1 What is Evolution? – The Process of Evolution
 Pesticide resistant lice are an example of biological
evolution.
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1 What is Evolution? – The Process of Evolution
 Natural selection – the differential survival and
reproduction of individuals in a population
 Process by which populations adapt to varying
environments
 Examples:
 Pesticide resistance in crop-eating insects
 Antibiotic resistance in infectious bacteria
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1 What is Evolution? – The Process of Evolution
 Microevolution – changes that occur within a
species and the characteristics of a population.
Easily observed, relatively non-controversial.
 Macroevolution – changes that occur, as a result
of microevolution, over long periods of time and
result in the origin of new species. Controversial
among non-biologists.
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1 What is Evolution? – The Theory of Evolution
 Ambiguity of the word “theory”
 Everyday usage: theory = best guess, or tentative
explanation
 Scientific usage: theory = body of accepted general
principles, supported by many lines of evidence.
 Examples: atomic theory, gravity, germ theory.
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1 What is Evolution? – The Theory of Evolution
 Theory of evolution
 All species present on earth today are descendents
of a single common ancestor, and all species
represent the product of millions of years of
accumulated evolutionary changes.
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1 What is Evolution? – The Theory of Evolution
 Theory of common descent
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BioFlix: Mechanisms of Evolution
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Animation: Principles of Evolution
Click “Go to Animation” / Click “Play”
2 Charles Darwin and the Theory of Evolution
 Theory of Evolution is sometimes called
“Darwinism” because Charles Darwin is largely
credited with introducing the concept to
mainstream science.
 Many philosophers of science before Darwin had
notions of organisms changing over time.
 Anaximander – Greek philosopher who suggested
that humans evolved from fish that had moved onto
land
 Lamarck – published ideas about inheritance of
acquired traits in 1809
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2 Charles Darwin and the Theory of Evolution - The
Voyage of the Beagle
 At age 22, Darwin set sail as ship’s naturalist
aboard the HMS Beagle on a five year long trip.
 Darwin’s job was to collect and observe “anything
worthy to be noted for natural history.”
 Darwin had a book by Lyell, Principles of Geology,
which postulated earth was old and changes
occurred over long periods of time.
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2 Charles Darwin and the Theory of Evolution - The
Voyage of the Beagle
 The following had influences on Darwin during the
voyage:
 Rainforests of Brazil
 Fossils that he collected
 Birds and reptiles of the Galapagos Islands
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2 Charles Darwin and the Theory of Evolution The Voyage of the Beagle
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2 Charles Darwin and the Theory of Evolution Developing the Hypothesis of Common Descent
 Darwin returned to England in 1836, but did not
publish his ideas immediately.
 Spent about 20 years refining his ideas
 Learned about animal husbandry (selective breeding)
 Finally published On the Origin of Species in 1858
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2 Alternative Ideas on the Origins and Relationship
among Organisms
 Theory of common descent is controversial. There
are some possible alternative hypotheses that can
be tested against available data.
 Static model hypothesis
 Transformation hypothesis
 Separate types
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2 Alternative Ideas on the Origins and
Relationship among Organisms
 Graphical
representations
of theory of
common
descent and
alternative
hypotheses:
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Figure 9.7
3 Examining the Evidence for Common Descent
 Several lines of biological evidence point to a
common ancestor:
 Biological classification
 Anatomical similarities between organisms
 Useless traits in modern species
 Shared developmental pathways
 DNA similarities
 Distribution of organisms on earth (biogeography)
 Fossil evidence
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3 Examining the Evidence for Common Descent
 Biological classification implies common
ancestry.
 Linnaean Classification
 Gives each species a two-part or binomial name in
Latin
 Carolus Linnaeus groups organisms in a hierarchy
going from broadest to narrowest groupings
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3 Examining the Evidence for Common Descent
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3 Examining the Evidence for Common Descent
 Anatomical homology
 Mammalian forelimbs have the same set of bones.
The underlying structure is similar despite the very
different functions.
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3 Examining the Evidence for Common Descent
 Useless traits in modern species
 Vestigial traits are traits that function in one
organism but are greatly reduced in others
 For example:
 Ostrich and penguins form wings but do not fly
because the wings are non-functional
 Humans have a tailbone by have no tail
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3 Examining the Evidence for Common Descent –
Developmental Homologies
 A consequence of shared developmental pathways
is similarity among chordate embryos
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3 Examining the Evidence for Common Descent –
Molecular Homology
 DNA similarities
 Birds in same genus have DNA that is more similar
to one another, while distantly-classified birds have
DNA that is less similar.
 Molecular clock allows the use of DNA sequence
differences between species to determine when
they diverged from their common ancestor.
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3 Examining the Evidence for Common Descent –
Biogeography
 Biogeography is the distribution of species on
earth.
 Different species of mockingbird found on
Galapagos all resemble another species found
on the mainland.
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3 Examining the Evidence for Common Descent –
The Fossil Record
 Fossils are remains of living organisms left in
soil or rock.
 Horse fossils provide a good sequence of
evolutionary change within a lineage.
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3 Examining the Evidence for Common Descent –
The Fossil Record
 Fossilization is the formation of fossils
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3 Examining the Evidence for Common Descent –
Fossil Record
 Bipedal humans have some unique anatomical
traits, such as features of hips, knees, and skull.
 Anatomical differences between humans and
chimpanzees allow for identification of fossils
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3 Examining the Evidence for Common Descent –
Radiometric Dating
 Radiometric dating
 Used to determine age of rocks
 Relies on decay of radioactive isotopes into daughter
products
 The rate of decay is measured by the element’s
half-life
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3 Examining the Evidence for Common Descent –
Radiometric Dating
 Using radiometric dating, scientists have estimated
the age of fossil hominims.
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3 Examining the Evidence for Common Descent –
Radiometric Dating
 Trends in human evolution
 Larger brains, Flatter face, Reduced jaw size
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4 Are Alternatives to the Theory of Evolution
Equally Valid?
 The same lines of evidence that support common
descent can be used to look for the closest relatives
of humans.
 Table 10.1 summarizes the evidence for common
descent.
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4 Are Alternatives to the Theory of Evolution
Equally Valid?
 Weighing the alternatives
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4 Are Alternatives to the Theory of Evolution
Equally Valid? – The Origin of Life
 The origin of life
 Evolution is the study of how life changes.
 It doesn’t really address issue of how life began.
 Experiment evidence does give some clues
about beginnings of life.
 Evidence for the theory of common descent
demonstrates consilience.
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4 Are Alternatives to the Theory of Evolution
Equally Valid?
 Evolutionary theory informs all aspects of modern
biology.
 Evolutionary theory helps us understand the function
of human genes.
 Evolutionary theory is important to understanding
species interactions.
 Evolutionary theory is important for predicting the
biological consequences of climate change.
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Which of the following is not an example of a
scientific theory?

gravity

evolution

intelligent design

all of the above
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Which of the following is not an example of a
scientific theory?

gravity

evolution

intelligent design

all of the above
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The head lice that have become resistant to the
pesticide permethrin demonstrate microevolution.
True or False: The individual head lice have
evolved.

True.

False.
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The head lice that have become resistant to the
pesticide permethrin demonstrate microevolution.
True or False: The individual head lice have
evolved.

True.

False.
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Giraffes stretched their necks by reaching for high
leaves. They then passed this longer neck to their
offspring. Who thought of this idea?

Darwin

Lyell

Lamarck

Wallace
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Giraffes stretched their necks by reaching for high
leaves. They then passed this longer neck to their
offspring. Who thought of this idea?

Darwin

Lyell

Lamarck

Wallace
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Which correctly lists the classification levels from
broadest to narrowest groupings?

Order, Family, Genus, Species

Family, Genus, Order, Species

Species, Genus, Family, Order

Order, Species, Family, Genus
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Which correctly lists the classification levels from
broadest to narrowest groupings?

Order, Family, Genus, Species

Family, Genus, Order, Species

Species, Genus, Family, Order

Order, Species, Family, Genus
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Which of the following do not belong in the order
Primates.

monkeys

humans

apes

all of the above belong to the order Primates
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Which of the following do not belong in the order
Primates.

monkeys

humans

apes

all of the above belong to the order Primates
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Which of the following is an example of a vestigial
trait?

a human tailbone

a dolphin’s blowhole

a gorilla’s opposable thumb

a penguin’s flippers
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Which of the following is an example of a vestigial
trait?

a human tailbone

a dolphin’s blowhole

a gorilla’s opposable thumb

a penguin’s flippers
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Where did humans evolve?

North America

Europe

Africa

Galapagos Islands
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Where did humans evolve?

North America

Europe

Africa

Galapagos Islands
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True or False: Differences in DNA sequences can
help determine when two species diverged from
their common ancestor.

True.

False.
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True or False: Differences in DNA sequences can
help determine when two species diverged from
their common ancestor.

True.

False.
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What proposed mechanism of evolution is shown in
this figure?

static model

transformation

separate types

common descent
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What proposed mechanism of evolution is shown in
this figure?

static model

transformation

separate types

common descent
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What is shown by the y-axis of this graph?

percentage of
parent element
remaining

time (in millions
of years)

depth of burial

number of
fossils found
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What is shown by the y-axis of this graph?

percentage of
parent element
remaining

time (in millions
of years)

depth of burial

number of
fossils found
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