Download Chapter 9: Evolution

Chapter 9
Where Did We Come From?
The Evidence for Evolution
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Chapter 9 Section 1
What is Evolution?
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9.1 What is Evolution?
What is Evolution?
 Two different ways scientists think of
evolution
1. The Process of Evolution
2. The Theory of Evolution
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9.1 What is Evolution?
The Process of Evolution
 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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9.1 What is Evolution?
Definitions
 Species = a group of individuals that:
 Can regularly breed together
 Can produce fertile offspring
 Are distinct from other species in appearance
or behavior.
 Population = a group of individuals of a
species that are separated by geography.
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9.1 What is Evolution? - The Process of
Evolution
Example
 Pesticide resistant lice are an example of
biological evolution.
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Figure 9.1
9.1 What is Evolution? -The Process of
Evolution
Populations evolve, NOT individuals.
 In the lice example, the genetic structure of the
population of lice changed.
 Individuals without a gene for resistance died
 But individuals with resistance survived to
breed again
 Over time, the population changed to mostly
resistant individuals
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9.1 What is Evolution? -The Process of
Evolution
Why do populations evolve?
 Natural selection = the differential
survival and reproduction of individuals in
a population.
 Process by which populations adapt to
changing environments
 Examples:
 Pesticide resistance in crop-eating insects
 Antibiotic resistance in infectious bacteria
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How Natural Selection Works
1. Offspring have different traits, some of which are
inheritable.
2. Some traits are beneficial, and help the
individual to survive, whereas others are harmful.
3. Organisms produce more young than can
survive.
4. Organisms with beneficial traits have a better
chance of surviving and passing on their
characteristics to the next generation than those
with harmful traits.
5. Therefore, over time, beneficial traits are
perpetuated in the lineage, while harmful traits
disappear.
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9.1 What is Evolution?
Two different scales of evolution
1. Microevolution – changes that occur
within a species due to changing
characteristics of a population.

Easily observed, relatively non-controversial.
2. 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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9.1 What is Evolution? Theory of Evolution
The Theory of Evolution has Two Parts
 All species present on earth today:
1. Represent the product of millions of years
of accumulated evolutionary changes.
2. Are descendants of a single common
ancestor
 Aka the theory of common descent
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9.1 What is Evolution?
The Theory of Common Descent
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Figure 9.2
9.1 What is Evolution?
Why is it controversial?
 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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End Chapter 9 Section 1
What is Evolution?
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Chapter 9 Section 2
Charles Darwin and
the Theory of Evolution
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9.2 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.
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9.2 Charles Darwin
Early Views of Evolution
 Charles Darwin did not “invent” the idea of
evolution. Many philosophers of science
had notions of organisms changing over
time.
 Fossils had caused people to propose
animals evolved
 Anaximander – Greek philosopher (611-546
BC) who first suggested that humans
evolved from fish that had moved onto land
 Jean Baptiste Lamarck – published ideas
about inheritance of acquired traits in 1809
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9.2 Charles Darwin
The Voyage of the Beagle
 In 1831 at age 22, Darwin set sail as ship’s
naturalist aboard the HMS Beagle on a five
year long trip to map S. America.
 Darwin’s job was to collect and observe
“anything worth to be noted for natural
history.”
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9.2 Charles Darwin &Theory of Evolution
The Voyage of the Beagle
 The following had influences on Darwin
during the voyage:
 Darwin had a book by Lyell, Principles of
Geology, which postulated earth was old and
changes occurred over long periods of time.
 Rainforests of Brazil
 Fossils that he collected
 Birds and reptiles of the Galapagos Islands
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9.2 Charles Darwin & the Theory of Evolution
The Voyage of the Beagle
Galapagos islands tortoises vary with their
environments.
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Figure 9.5
9.2 Charles Darwin & 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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End Chapter 9 Section 2
Charles Darwin and
the Theory of Evolution
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Chapter 9 Section 3
Examining the Evidence
for Evolution
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9.3 Examining the Evidence for Evolution
Evolution versus Creation
 Intelligent Design and Creation
 God created organisms during 6
days as described in Genesis
 Life has not significantly changed
since then
 Some claim creation occurred
recently, within the past 10,000
years
 Science can NOT test hypothesis
based upon supernatural forces
 But physical aspects can be tested
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9.3 Examining the Evidence for Evolution
Four Proposed explanations
for life on earth
1. Static model hypothesis
(creation or intelligent
design)
2. Transformation hypothesis
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9.3 Examining the Evidence for Evolution
Four Proposed explanations
for life on earth
3. Separate Types Hypothesis
4. Theory of Common Origin
(theory of evolution)
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9.3 Examining the Evidence for Evolution
An Overview of Evidence for Evolution
 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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9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Biological classification implies common
ancestry.
 Carl Linnaeus
 1707-1778.
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Figure 9.8
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Anatomical similarities between organisms.
Mammalian forelimbs have the same set of
bones. The underlying structure is similar despite
the very different functions.
Humerus
Radius
and ulna
Carpals
Metacarpals
Phalanges
Bat
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Sea lion
Lion
Chimpanzee
Human
Figure 9.9
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Vestigial & useless traits in modern
species.
 Tail bones in humans
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9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Shared developmental pathways.
Similarity among chordate embryos.
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Figure 9.11
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 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.
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Figure 9.12
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
Biogeography
 Distribution of
organisms on
earth.
 Different species of
mockingbird found
on Galapagos all
resemble another
species found on
the mainland.
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Figure 9.13
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Fossil evidence.
 Horse fossils provide a good sequence of
evolutionary change within a lineage.
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Figure 9.14
9.3 Examining the Evidence for Evolution
PLAY
Animation—Principles of Evolution
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End Chapter 9 Section 3
Examining the Evidence
for Evolution
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Chapter 9 Section 4
Part A
Are Alternatives to the Theory of
Evolution Equally Valid?
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9.4
Are Alternatives to the Theory of Evolution Equally Valid?
 Weighing the Alternatives
Static model
Rejected
Earth is far older than
10,000 years, and
species have clearly
changed over time.
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Transformation
Rejected
Evidence of relationships
among organisms abound.
Separate types
Rejected
Universality of DNA,
genetic code, and cell
components are
evidence of a single
origin of all life.
Common descent
Supported by a wide
variety of evidence,
including comparative
anatomy, DNA
sequences, and the
fossil record.
Figure 9.27
9.4
Are Alternatives to the Theory of Evolution Equally Valid?
Static Model
 Predicts earth is less than 10,000
years old
 Radiometric dating proves earth is far
older
 Predicts all species arose
individually and have not changed
 Fossil evidence proves organisms
have changed over time
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Figure 9.27
9.4
Are Alternatives to the Theory of Evolution Equally Valid?
Transformation Model
 Predicts species arose separately and
then evolved, but no new species
 No reason to expect different species
would share structures
 Especially vestigial structures
 No reason to expect similarities in
DNA sequences
 Predicts little evidence of relatedness
 Abundant evidence of species
relatedness
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Figure 9.27
9.4
Are Alternatives to the Theory of Evolution Equally Valid?
Separate Types Model
 Predicts that different groups arose
separately and then evolved new species
 No reason to expect genetic code to be
universal
 But genetic code is universal
 Method for translating genes into
proteins is universal
 EXP: Genes from bacteria can be put
into plants, which then make bacterial
proteins
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Figure 9.27
9.4
Are Alternatives to the Theory of Evolution Equally Valid?
Common Descent Model
 Predicts that species evolved from common
ancestor
 Supported by:
 Biological classification
 Anatomical homology
 Vestigial traits
 Biogeography
 Homology of development
 Homology of DNA
 Fossil Record
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Figure 9.27
Chapter 9 Section 4
End Part A
Are Alternatives to the Theory of
Evolution Equally Valid?
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Chapter 9 Section 4
Part B
How Did Life Begin?
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9.4 The Origin of Life
The Origin of Life
 Evolution is the study of how life changes
 It doesn’t address how life first began
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9.4 The Origin of Life
A Hypothesis for Origin of Life from
Nonliving Precursors
1. Simple molecules present early in earth’s
history (CH4, NH3, H2O, H2) assembled into
more complex molecules (such as
nucleotides & amino acids)
2. These molecules assembled into chains
that could store information (nucleic acids
& proteins)
3. These more complex molecules became
organized into self-replicating “cells”
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9.4 Experiment evidence does give some
clues about beginnings of life
Origin of life
 The Miller-Urey
experiment in 1953
demonstrated that
complex molecules
can spontaneously
form from simple
chemicals.
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Figure 9.29
9.4 Experiment evidence does give some
clues about beginnings of life
Origin of life
1. The Miller-Urey experiment demonstrated
that complex molecules can spontaneously
form from simple chemicals.
2. Later experiments showed that simple
precursors spontaneously form polymers to
form proteins, DNA and RNA when put into
contact with hot sand, clay or rock
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Figure 9.29
9.4 Experiment evidence does give some
clues about beginnings of life
3. In 1980 scientists showed RNA, which
carries genetic info., could copy itself

Demonstrated capacity for self-replication
4. Phospholipids put into water
spontaneously form cell like lipid bilayers
Conclusions
 These experiments suggest life could have
started spontaneously in earths early
environment
 No one has been able to create life as we
know it in the lab
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9.4 Importance of The Theory of Evolution
Importance of The Theory of Evolution
 Evolutionary theory informs all aspects of
modern biology.
 It is important because it helps scientists
grapple with modern issues.
 Examples:
 To understand the function of human genes
 To understanding species interactions
 For predicting the biological consequences of
climate change
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End Chapter 9 Section 4
Part B
How Did Life Begin?
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End Chapter 9
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