Lecture 14: Darwin and evolution

1
Lecture 14 Darwin and evolution
Assigned Readings Ch. 22
The evolution controversy Darwin and his voyage o
f discovery. Darwin FitzRoy the Beagle aroun
d the world Galapagos archipelago adaptation
The Origin of Species and Darwins arguments for
natural selection. 1859 Wallace Darwin as a sc
ientist other work coral reefs Main Ideas in t
he Origin descent with modification and natural
selection phylogenetic trees, fossil, fossil
record, heritable variation overproduction of
offspring environmental selection,
use and disuse of characters, acquired
characters. lack of inheritance of acquired
character, artificial selection, cultivation
cultivated varieties  Aspects of biology explaine
d by Darwinian evolution . adaptation in real t
ime (observable in human lifetime or recorded
human history) homology (anatomical,
embryological, molecular) biogeography and
convergent evolution
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The evolution controversy
Which is the real Darwin?
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
Charles Darwin failed medical student, failed
divinity student, ardent beetle collector.
Parts of the following slides are condensed in
Fig. 22.5
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
Voyage of H.M.S. Beagle, 1831 - 1836
90 feet of ship, 74 people living together for 5
years...
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
Sir Robert FitzRoy Commander of the Beagle at ag
e 26 (the youngest captain ever in the history of
Her Majesties Navy).
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
Brazil thrilled by rainforest, appalled by
slavery
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
Galapagos archipelago volcanic islands less than
15 MY of age.
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Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation
High lush island
Low, desert island
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Basis of natural selection three generalizations
about the properties of organisms
Darwin Darwin the Beagle FitzRoy the world Ga
lapagos
adaptation

• 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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The Origin 1859 Wallace
1859
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Darwin and Wallace (1823-1913)
The Origin 1859 Wallace

• 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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The Origin 1859 Wallace
Two of Wallaces books were titled Natural
Selection and Darwinism
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Darwin as a scientist
Darwin as a scientist other work coral reefs

• Darwin thought of himself as a theoretical
  scientist
  
• curiosity-dissatisfaction-speculation-hypothesis-d
  erivative predictions
  
• some of Darwins studies
• formation of coral reefs
• evolution by means of natural selection
• sexual selection
• sexual reproduction in plants
• origin of emotions and human language
• origin of humans
• formation of soils as a result of biological
  activities

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Darwin as a scientist other work coral reefs
Darwin saw Pacific atolls and islands as part of
a geological sequence
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Darwin as a scientist other work coral reefs
Darwins later life funded by the Wedgewood
family.
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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
Fig. 22.7. One of Darwins two main contributions
in the Origin is the idea of Descent with
modification - as seen with the relationships of
elephants. This is a phylogeny (graph showing
relationships) or phylogenetic tree, based on
both living species and those known from fossils
(remnants of bones etc. from the past). The
whole story of the past is contained in the
fossil record.
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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
Fig. 22.3. The fossil record provides much of
the documentation for Darwins idea of descent
with modification.
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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
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.
Fig. 22.8
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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
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. The environment is
doing the selection.
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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
Fig. 22.4. But one must be sure that the
variation is 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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Main Ideas in the Origin descent with modificatio
n (phylogenetic trees, fossil, fossil record)
natural selection (overproduction, heritable vari
ation, environmental selection, use and disuse
of characters, artificial selection)
Fig. 22.10. Artificial selection provided
support for the idea of natural selection. These
are cultivated varieties of wild mustard.
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Fig. 22.6. Adaptations to different diets in
Darwins finches
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Fig. 22.11. Some spectacular adaptations.
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Darwinian evolution explains Microevolution in
real time (observations and experiments)
Homology (anatomical, embryological, molecular)
Biogeography The fossil record
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22.13. Evolution of resistance in HIV (AIDs
virus) to a drug.
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22.14. Homologous structures with a common
history. Contrast with the analogous wings of
insects and birds. This is an example of
morphological (anatomical) analogy.
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22.15. Embryological/developmental homology
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22. 16. Molecular homology.
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22.17. Patterns in biogeography -
convergent evolution of flying squirrels and
sugar gliders.
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Darwinian explanations adaptation in real time

homology biogeography the fossil record
Fig. 22.18. Palaeontology - an example of a
transitional fossil (showing hindlimbs in a
fossil whale)
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Lecture 14 Darwin and evolution
Assigned Readings Ch. 22
The evolution controversy Darwin and his voyage o
f discovery. Darwin FitzRoy the Beagle aroun
d the world Galapagos archipelago adaptation
The Origin of Species and Darwins arguments for
natural selection. 1859 Wallace Darwin as a sc
ientist other work coral reefs Main Ideas in t
he Origin descent with modification and natural
selection phylogenetic trees, fossil, fossil
record, heritable variation overproduction of
offspring environmental selection,
use and disuse of characters, acquired
characters. lack of inheritance of acquired
character, artificial selection, cultivation
cultivated varieties  Aspects of biology explaine
d by Darwinian evolution . adaptation in real t
ime (observable in human lifetime or recorded
human history) homology (anatomical,
embryological, molecular) biogeography and
convergent evolution