Download BSC1005 /Belk_Chapter 9

Chapter 9
Where Did We Come From?
The Evidence for Evolution
PowerPoint lecture prepared by
James M. Hutcheon
Georgia Southern University
Copyright © 2010 Pearson Education, Inc.
What you must know at the end of this chapter
 1. Differentiate between population and
species
 2. Explain what is evolution and how it
happens. What is the mechanism of evolution?
Define three factors that influenced Darwin’s
proposal of natural selection
 3. Give examples of the seven sources of
evidence that support the theory of evolution
Copyright © 2010 Pearson Education, Inc.
9.1 What is Evolution? - The Process of
Evolution
 Biological evolution – change in the
characteristics of a population of organisms that
occurs over the course of generations (changes
in populations over long periods of time).
 Evolutionary changes are inherited via genes
 Other changes may take place because of
environmental changes and are not necessarily
evolutionary.
Copyright © 2010 Pearson Education, Inc.
9.1 What is Evolution? - The Process of
Evolution
 Pesticide resistant lice are an example of
biological evolution.
Initial lice infestation consists
of both susceptible and resistant
lice.
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After permethrin treatment, most lice
are dead, but a few that are resistant
to the pesticide survive.
Reinfestation with the offspring of the
resistant lice. The population of lice is
now more resistant to permethrin.
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
 Over time, the population changed to mostly
resistant individuals
Copyright © 2010 Pearson Education, Inc.
9.1 What is Evolution? -The Process of
Evolution
 Natural selection – the differential
survival and reproduction of individuals in
a population.
 How do populations adapt to different
environments?
 Natural selection is the process by which
populations adapt to varying environments
 Examples:
 Pesticide resistance in crop-eating insects
 Antibiotic resistance in infectious bacteria
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9.1 What is Microevolution? Macroevolution?
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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9.1 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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9.1 What is Evolution? - The 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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9.1 What is Evolution? - The Theory of
Evolution
Time (thousands of generations)
Organisms observed today
Evolution
Evolution
Common ancestor
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Figure 9.2
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.
Copyright © 2010 Pearson Education, Inc.
9.2 Charles Darwin and the Theory of
Evolution - Early Views of Evolution
 Charles Darwin did not “invent” the idea of
evolution. Many philosophers of science
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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9.2 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 worth 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.
Copyright © 2010 Pearson Education, Inc.
9.2 Charles Darwin and the Theory of
Evolution - The Voyage of the Beagle
 The following had influences on Darwin
during the voyage:
 Reading Lyell and Hutton’s theories about
the Earth
 Rainforests of Brazil
 Fossils that he collected
 Birds and reptiles of the Galapagos Islands
Copyright © 2010 Pearson Education, Inc.
 Evolution explains the unity and diversity of life
Evolution is the unifying theory of Biology
showing that all forms of life are related
 Charles Dar win
 Synthesized the theory of evolution by
natural selection
Figure 1.6A
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Darwin’s Voyage
 At age 22, Charles Darwin began a fiveyear, round-the-world voyage aboard the
Beagle
 In his role as ship’s naturalist he collected
and examined the species that inhabited
the regions the ship visited
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Voyage of the Beagle
Copyright © 2010 Pearson Education, Inc.
Darwin’s Voyage
 At age 22, Charles Darwin began a fiveyear, round-the-world voyage aboard the
Beagle
 In his role as ship’s naturalist he collected
and examined the species that inhabited
the regions the ship visited
Copyright © 2010 Pearson Education, Inc.
On the Origin of Species
 Darwin’s book
 Published in 1859
 Laid out in great detail his evidence in
support of the theory of evolution by
natural selection
 Alfred Wallace had a manuscript with the
same ideas about evolution and natural
selection.
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9.2 Charles Darwin and 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 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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9.3 Examining the Evidence for Evolution
 Theory of common descent is
controversial. There are some possible
alternative hypotheses that can be tested
against available data (each explained in
subsequent slides):
 Static model hypothesis
 Transformation hypothesis
 Separate types
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution
 Graphical representations of theory of common
descent and alternative hypotheses:
(b) Transformation
Species arise separately but do change over time in
order to adapt to the changing environment.
Time
Time
(a) Static model
Species arise separately
and do not change over time.
Difference in form
Difference in form
Copyright © 2010 Pearson Education, Inc.
Difference in form
(d) Common descent
Species do change over time, and new
species can arise. All species derive
from a common ancestor.
Time
Time
(c) Separate types
Species do change over time, and new species
can arise; but each group of species derives from
a separate ancestor that arose independently.
Difference in form
Figure 9.7
9.1 What is Evolution? - The Theory of
Evolution
PLAY
Animation—Principles of Evolution
http://media.pearsoncmg.com/bc/bc_0media_bio/blast/index.htm?natural_selection#An
im
This animation about natural selection
http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?bb3evolution
This animation about the mechanism of evolution
http://media.pearsoncmg.com/bc/bc_0media_bio/blast/index.htm?homologous_limb_e
vo
This animation about similarities of the limbs of mammals
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution - An
Overview of Evidence for Evolution
 Several lines of biological evidence point to a
common ancestor and Evolution:
 Biological classification
 Anatomical similarities between organisms
(homology)
 Useless traits in modern species (vestigial
structures)
 Shared developmental pathways
 DNA similarities
 Distribution of organisms on earth (biogeography)
 Fossil evidence
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution An Overview of Evidence for Evolution
 Biological classification implies common
ancestry. As the groups become smaller the organisms have more
similarities. The groups imply evolutionary relationships among organisms.
Bread yeast
Chitridomycota
(water molds)
Zygomycota
(bread molds)
Morels Leaf rusts Mushrooms Class
Ascomycota
Fungi
Basidomycota
Phylum
Kingdom
Common ancestor
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Figure 9.8
9.3 Examining the Evidence for Evolution - A
Closer Look
 Linnean classification
 Basis of modern biological classification
 Named after Carl von Linneaus
 Hierarchical: large groups share general
characteristics, and small groups share
many characteristics.
 Humans are classified with apes because
they share many biological characteristics
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution - A
Closer Look
 Linnean
classification of
humans
Domain
(Eukarya)
Kingdom
(Animalia)
Phylum
(Chordata)
Class
(Mammalia)
Order
(Primates)
Family
(Hominidae)
Genus
(Homo)
Species
(Homo sapiens)
Copyright © 2010 Pearson Education, Inc.
Figure 9.16
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 (homology). Evolution led to
modifications on each group.
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 STRUCTURES-Useless traits in modern
species these are reminders of our biological heritage.
Example: Vestigial, but similar, structures in ferns and
flowering plants. Primitive plants had 2 stages in their life
sporophyte and gametophyte. Modern flowering plants no longer have
2 stages but still produce a gametophyte
(a) Fern gametophyte
(b) Flower ovary
Gametophyte
generation
is found here.
Copyright © 2010 Pearson Education, Inc.
Figure 9.10
Vestigial Structures
 The wings of ostriches
 Tail bones in humans and the great apes (lost after
embryonic life)
 Our appendix
 Our wisdom teeth
 Arrector pili muscles to elevate hair (our goose
bumps)
 Whales pelvic bone
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution - A
Closer Look
 Anatomical and developmental similarities
 Tail – great apes and humans have tailbone,
but no tail
“Useful” trait in primate relative
Vestigial trait in human
(a) Tail bone
Copyright © 2010 Pearson Education, Inc.
Figure 9.18a
9.3 Examining the Evidence for Evolution - A
Closer Look
 Anatomical and developmental similarities
 Goosbumps – arrector pili are small muscles at
base of body hair. When tensed cause hair to stand
up. Useful for heat conservation or in aggressive
social exchange.
(b) Goose bumps
Copyright © 2010 Pearson Education, Inc.
Figure 9.18b
9.3 Examining the Evidence for Evolution - An Overview of Evidence for
Evolution
 Shared developmental pathways. Similarity
among chordate embryos. Early embryos all
look very similar, all have pharyngeal slits and tails
suggesting a common ancestor.
Snake
Early
embryo
Chicken
Possum
Cat
Bat
Human
Pharyngeal
slits
Tail
Intermediate
embryo
Late
embryo
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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 distantlyclassified birds have DNA that is less similar.
 DNA sequence comparisons show that organisms that are
related share many genes however the sequence of these
genes is not the same. Ex: humans and chimpanzees share
99.01% DNA
Ruddy turnstone
Black turnstone
Red knot
Caspian tern
100%
90%
82%
72%
% DNA similarity
to Ruddy turnstone
Same genus
(Arenaria)
Same family
(Scolopacidae)
Same order
(Charadriiformes)
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Figure 9.12
9.3 Examining the Evidence for Evolution - An Overview of Evidence for
Evolution- Evidence from Biogeography
 Distribution of
organisms on earth.
Different species of
mockingbird found on
Galapagos all resemble
another species found
on the mainland.
Related species should
be found close to one
another.
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Figure 9.13
9.3 Examining the Evidence for Evolution - An Overview of
Evidence for Evolution- Fossil: remains of living organisms left in
soil or rock
 Fossil evidence. Horse fossils provide a good
sequence of evolutionary change within a
lineage. (we can estimate the age of a fossil by
radiometric dating)
Equus
Merychippus
1 toe
Mesohippus
3 toes
Hyracotherium
(Eohippus)
3 toes
4 toes
Modern horse
Horse ancestor
55
40
17
4
Millions of years ago
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Figure 9.14
9.3 Examining the Evidence for Evolution - A
Closer Look
 Evidence from fossils
 Radiometric dating
 Used to determine age of rocks
 Relies on decay of radioactive isotopes into
daughter products
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution - A
Closer Look
 The same lines of
evidence that
support common
descent can be
used to look for the
closest relatives of
humans.
 Are humans related
to apes?
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Figure 9.15
Evolution of humans- common ancestors
 https://www.23andme.com/gen101/prehist
ory/prologue/
Copyright © 2010 Pearson Education, Inc.
9.3 Examining the Evidence for Evolution - A
Closer Look
 Shared characteristics of humans and apes
Order Primates
Family Hominidae
Subfamily Homininae
Squirrel
monkey
Orangutan
Gorilla
Common
chimpanzee
Bonobo
Human
increase in size of
genital structures
delayed sexual maturity
broad incisors
shortened canine teeth
enlarged brow ridges
elongated skull
reduced hairiness
large brain
no tail
more erect posture
increased flexibility of thumb
Mammal ancestor
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Figure 9.17
9.3 Examining the Evidence for Evolution - A
Closer Look
 Evidence from molecular homology
African
monkey
96.66%
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Gorilla
98.90%
Chimpanzee
99.01%
Human
100%
Figure 9.19
9.3 Examining the Evidence for Evolution - A
Closer Look
 Bipedal humans have some unique anatomical
traits, such as features of hips, knees, and skull.
Chimpanzee
Human
Foramen
magnum Base of
skull
Back of
skull
Pelvis
Accommodate
four-legged
stance
Modified
for upright
stance
Limbs relative
to body
Larger
arms
Larger
legs
Feet
Grasping
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Weight bearing
Figure 9.21
9.3 Examining the Evidence for Evolution - A
Closer Look
 Early hominim
fossils such as
“Lucy” provide
evidence that the
earliest human
ancestors arose in
Africa.
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Figure 9.22
9.3 Examining the Evidence for Evolution - A
Closer Look
 Using radiometric dating, scientists have
estimated the age of fossil hominims.
Chimpanzee
Homo sapiens
Homo
neanderthalensis
Homo erectus
Millions of years ago
Paranthropus
robustus
Paranthropus
boisei
Homo habilis
Australopithecus
garhi
Paranthropus
aethiopicus
Australopithecus
africanus
Australopithecus afarensis
Ardepithecus
ramidus
Australopithecus anamensis
Hominin ancestor
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Figure 9.24
9.3 Examining the Evidence for Evolution - A
Closer Look
 Trends in human evolution
 Larger brains
 Flatter face
 Reduced jaw size
Australopithecus
afarensis
Age of fossil as
Ancient hominin
determined by
radiometric dating
3.5
(million years ago)
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Australopithecus
africanus
Homo
habilis
Homo
sapiens
Modern hominin
2.8
1.7
0
Figure 9.26
9.3 Examining the Evidence for Evolution
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Table 9.1
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?
 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
Copyright © 2010 Pearson Education, Inc.
9.4 Are Alternatives to the Theory of
Evolution Equally Valid? - The Origin of Life
Gases (CH4, NH3,
H2O, H2)
 The Miller-Urey
experiment
demonstrated that
complex molecules
can spontaneously
form from simple
chemicals.
Electrodes
2 Energy applied in the
form of heat and
electrical charges
Condenser
Water
vapor
3 Organic molecules
collected from the
system
1 Inorganic molecules,
including water and
methane, added to
system
Water droplets
Water
Heat
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Figure 9.29
9.4 Are Alternatives to the Theory of
Evolution Equally Valid?
 Evolutionary theory informs all aspects of
modern biology. It is important to
understand it because it helps scientists
grapple with modern issues.
 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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9.3 Examining the Evidence for Evolution - A
Closer Look
 Evidence from fossils
(a)
(b)
Radioactive element
Percentage of parent element remaining
Daughter product
Magma 1.8
million years
old
Decay curve
If 19% of the radioactive element
remains in a rock sample, and...
if the half-life of the radioactive
element is 1 million years, then...
... the age of the rock sample is
2.5 x 1 million = 2.5 million years.
Fossils between
1.8–2.5 million
years old
Magma 2.5
million years
old
Number of half-lives
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Figure 9.23
Review questions
 What is a population? What is a species?
 What factors influenced Charles Darwin’s proposal of the “Theory of
Evolution”? Who was Alfred Wallace? Who was Lyell?
 What does the theory of evolution says? Include at least two
important statements.
 List the alternative theories that exist (What are the four hypotheses about the
origin of modern organisms). Are alternative theories of evolution equally
valid as science? Explain.
 Explain how natural selection works.
 Explain the role of natural selection in the development of antibiotic
resistant microorganisms.
 Examine and give examples of the six sources of evidence that
support the theory of evolution?
 What is homology? What is a fossil? What are the levels of
classification and which one is the one where organisms share the
most similarities?
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