Exam Announcements

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Exam Announcements

• Exam is Thursday February 23 from 7-9 PM
• Details www.life.uiuc.edu/ib/150/Examoneinfo.html
• Exam is multiple choice, 72 questions
• Conflict Exam - requests to take the conflict
  exam must be made to Tracey Hickox,
  hickox_at_life.uiuc.edu, not later than 5 PM on
  Friday

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Exam Location

• 1 IF YOUR TA IS CHRISTINE or JENNY GO TO 112
  GREGORY HALL
• 2 IF YOUR TA IS BETH or EMILY GO TO 141 WOHLERS
  HALL
• 3 IF YOUR TA IS HELEN or BEN GO TO 114 DAVID
  KINLEY HALL
• 4 IF YOUR TA IS MAHESHI GO TO 23 PSYCHOLOGY
  BUILDING

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5 PM, Tuesday the 21st 228 Natural History
Building
Dr. Pennock - witness at the recent trial in
Dover, PA over teaching of Intelligent Design
Presented by UIUC Darwin Club
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Lecture 11 An overview of evolution
Assigned Readings Ch. 22
Life and Times of Chuck Darwin video The Theory
Wallace, Natural Selection, Descent with
Modification Darwins Evidence for Natural
Selection Artificial Selection, Limits on
Reproduction, Fit of Organisms to Their
Environment Darwins Evidence for Common
Ancestry fossil record, comparative morphology
(homology, vestigial structures, convergence),
biogeography
Evidence for Evolution Since Darwin experimental
and observational studies of evolution (guppies,
finches), molecular unity of life, developmental
biology Evolution Controversies? microevolution,
macroevolution  Evolution as Science methodologi
cal naturalism, confusing social/moral/religious
conflict with scientific conflict, modification
of evolutionary theory
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Darwin and Wallace (1823-1913)

• Darwin developed ideas on natural selection in
  early 1840s (1844 essay), but did not publish
• received a letter from Wallace in 1858 outlining
  natural selection
• 1858 presentation in London of Wallaces and
  Darwins work
• 1859 publication of Origin of Species

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Darwins Theory Has 2 Components

• Descent with Modification - What has happened to
  produce the diversity of life we see on earth
  today
• Natural Selection - The mechanism that driven the
  evolutionary change. Natural Selection was
  Darwin and Wallaces key innovation and why we
  call it a theory

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Basis of natural selection three generalizations
about the properties of organisms

• individual members of any species vary somewhat
  from one another
• this individual variation is heritable
• organisms can multiply at a rate that exceeds the
  capacity of the environment to support them
  (Malthus)

The result of the process of natural selection is
adaptation.
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Fig. 22.8
One of the observations that lead to the theory
of natural selection overproduction of
offspring. Malthus had argued that human
populations can increase exponentially, while
food production can only increase linearly, with
time.
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Fig. 22.9
A second observation that lead to the theory of
natural selection heritable variation exists for
all kinds of traits (features, characteristics)
of organisms. Putting observation one and two
together leads to the deduction of natural
selection genotypes that survive/reproduce best
replace other genotypes.
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Fig. 22.7. Darwins other main contribution in
the Origin is the idea of Descent with
modification - as seen with the relationships of
elephants.
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Darwin published his theory and supporting
evidence in The Origin of Species in 1859
This book contains not only the details of his
argument but also evidence for both
natural selection and common descent
What kinds of evidence?
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Evidence for Natural Selection

• Variation and Heritability (earlier)
• Nature Red in Tooth and Claw
• Fit of Organisms to Their Environment
• Ability of Artificial Selection to Produce New
  Varieties

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Resources are Always Limited

• Darwin noted that populations can always grow if
  they have enough resources, meaning that they
  will grow until there is competition for
  resources.

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Fig. 22.11. Some spectacular adaptations.
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Fig. 22.10. Artificial selection provided
support for the idea of natural selection. These
are cultivated varieties of wild mustard.
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Evidence for Descent with Modification

• The Fossil Record
• Comparative Morphology
• homology and vestigial structures
• convergence
• Biogeography, particularly of islands

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Fig. 22.3. The fossil record provides much of
the documentation for Darwins idea of descent
with modification.
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Fig. 22.14. Homologous structures with a common
history. Contrast with the analogous wings of
insects and birds.
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Fig. 22.18. Palaeontology - an example of a
transitional fossil (showing hindlimbs in a
fossil whale)
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Fig. 22.17. Patterns in biogeography -
convergent evolution of flying squirrels and
sugar gliders.
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Galapagos archipelago volcanic islands less than
15 MY of age.
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Low, desert island
High lush island
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Fig. 22.6. Adaptations to different diets in
Darwins finches
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Evidence for Darwins Ideas Since Then

• Evolution of Diseases, Pests, and Weeds
• Observation of Natural Selection in the Wild
• Molecular Homologies and the Unity of Life at the
  Cellular Level
• Developmental Biology

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Fig. 22.13. Evolution of resistance in HIV (AIDs
virus) to a drug.
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How observations and real time experiments with
Guppies (Poecillia reticulata) have helped us
explain natural selection They are classic
examples of artificial selection Observations,
field transplantation experiments and lab
experiments have shown that predators cause the
evolution of dull colors in males. Observations,
field transplantation experiments and lab
experiments have shown that predators cause the
evolution of varying ages of sexual maturity.
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Wild guppy males from the same stream in
Trinidad. (a) fish from above a waterfall (no
predators of adult fish) (b) with
predators). Aquarium experiments with (a) fish
kept with a serious predator caused them to
evolve to look like (b) fish. Transplanting (b)
type fish to a stream with no guppies and weak
predators cause them to evolve to (a).
a
b
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Molecular Homology

• Descent with Modification operates on the
  molecular level. There are also vestigial
  molecules (non-coding DNA).
• Similar species have similar molecules even when
  there is no functional reason for them to do so.

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Fig. 22. 16. Molecular homology.
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Developmental Biology

• Scientists have often noticed that early
  developmental stages of organisms share similar
  characteristics
• Studies of the genetics of development (remember
  mitosis lecture?) have revealed common patterns
  of genetic control of development in very
  different animals

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Fig. 22.15. Embryological/developmental homology
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Evolution as Science

• Evidence for Evolution and the modification of
  evolutionary biology
• Inference and Observation and Scientific Evidence
• History of Evolution and Opposition to Evolution

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Fig. 22.4. For evolution to work variation must
be heritable Evolution of acquired characters
(as proposed by Lamarck) has not been shown to
exist. (However, Darwin accepted this because he
had not read his copy of Mendels paper- he
referred to use and disuse of characters as a
part of his theory).
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Modifying Darwins Ideas

• Genetics - initially confused biologists who
  thought it was an alternative to natural
  selection
• It took 50 years to refine Darwins ideas to fit
  them into a genetic framework
• Is this a strength or a weakness?

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microevolution
macroevolution
years 10 100 1000
106 109
drug resistance
origin of life
color forms
major organ systems
anatomical change
observation
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Inference the reasoning involved in drawing a
conclusion or making a logical judgment on the
basis of circumstantial evidence and prior
conclusions rather than on the basis of direct
observation. http//wordnet.princeton.edu/
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Crime Scene Inference
A lot of science and police work are based on
inference.
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microevolution
macroevolution
years 10 100 1000
106 109
drug resistance
origin of life
color forms
major organ systems
anatomical change
observation
intelligent design (too complex to evolve?)
scientific inquiry
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Science and Opposition to Evolution

• Science is based on uncertainty - rigor is needed
  to make ideas more certain - everything is open
  to critical inquiry
• Science, since the 18th century has been based on
  methodological naturalism - only study what you
  can observe (or infer from observation).

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Biblical Creationism and Intelligent Design

• Young Earth Creationism - specific model based on
  Genesis. Requires changes in physical nature of
  universe over time.
• Intelligent Design - negative argument, no
  specific model
• This does not mean that these arguments are
  necessarily wrong - just that they are not
  susceptible to scientific investigation

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Science and Morality

• Two separate things to consider
• Science as a factual matter is amoral - it makes
  no sense to discuss the morality of gravity or
  hydrogen bonds or evolution
• However
• Scientists and everyone else has a responsibility
  to consider the moral implications of research
  techniques and applications

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Lecture 11 An overview of evolution
Assigned Readings Ch. 22
Life and Times of Chuck Darwin video The Theory
Wallace, Natural Selection, Descent with
Modification Darwins Evidence for Natural
Selection Artificial Selection, Limits on
Reproduction, Fit of Organisms to Their
Environment Darwins Evidence for Common
Ancestry fossil record, comparative morphology
(homology, vestigial structures, convergence),
biogeography
Evidence for Evolution Since Darwin experimental
and observational studies of evolution (guppies,
finches), molecular unity of life, developmental
biology Evolution Controversies? microevolution,
macroevolution  Evolution as Science methodologi
cal naturalism, confusing social/moral/religious
conflict with scientific conflict, modification
of evolutionary theory