Darwin's Origin of Species: a guided tour

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Darwin's Origin of Species a guided tour

• Jeremy Fox
• Dept. of Biological Sciences
• University of Calgary

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(No Transcript)
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The origin of Darwin's Origin

• 1842 Sketches theory of evolution by natural
  selection

• 1854 Begins work on his "big book," Natural
  Selection

• 1858 Letter from Wallace prompts him to publish
  a short joint paper on the idea of natural
  selection

• Nov. 24, 1859 Publication of On the Origin of
  Species, an "abstract" of the "big book" (never
  completed)

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On the Origin of Species A tour of the first
edition
Read the 1st edition for free online http//www.l
iterature.org/authors/darwin-charles/the-origin-of
-species/
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Introduction
When on board H.M.S. 'Beagle' as naturalist, I
was much struck with certain facts in the
distribution of the inhabitants of South America,
and in the geological relations of the present to
the past inhabitants of that continent. These
facts seemed to me to throw some light on the
origin of species...
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The first organisms mentioned

• Familiar examples of adaptation

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Chapter I Variation under domestication
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Man's power of selection
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Chapter II Variation under nature
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What Darwin didn't know (and Mendel did) the
causes of variation and inheritance
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Chapter III Struggle for existence
Owing to this struggle for life, any variation,
however slight and from whatever cause
proceeding, if it be in any degree profitable to
an individual of any species, in its infinitely
complex relations with other organic beings and
to external nature, will tend to the preservation
of that individual, and will generally be
inherited by its offspring...I have called this
principle, by which each slight variation, if
useful, is preserved, by the term of Natural
Selection, in order to mark its relation to man's
power of selection. - Origin, p. 61.
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All ecology is footnotes to Darwin
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Chapter IV Natural selection
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So how do species originate, Mr. Darwin?

• The modern answer different selection pressures
  favoring different adaptations

• It helps if there is a barrier to gene flow
• physical barriers (e.g., islands in the ocean)
• behavioral barriers (e.g., mate choice)

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Darwin sometimes sounds modern...
"...after physical change of any kind,
immigration will be prevented, so that new places
in the polity of each island will have to be
filled up by modifications of the old
inhabitants and time will be allowed for the
varieties in each to become modified and
perfected." - Origin, pp. 107-108
...and sometimes not.

• Emphasizes "Principle of Divergence"
• Individuals will be fittest if they have
  divergent offspring

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Chapter V Laws of variation
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Chapter VI Difficulties of the theory
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What good is half an eye? Plenty!
Chlorella eyespot
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Chapter VII Instinct
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By the way...

• Self-sacrifice is explained by kin selection (!)

"...a slight modification of structure, or
instinct, correlated with the sterile condition
of certain members of the community, has been
advantageous to the community consequently the
fertile males and females of the same community
flourished, and transmitted to their fertile
offspring a tendency to produce sterile members
with the same modification." - Origin, p. 238

• Sterile worker castes refute Lamarckian evolution
  (!)

"For no amount of exercise...in the utterly
sterile members of a community could possibly
have affected the structure or instincts of the
fertile members, which alone leave descendents. I
am surprised that no one has advanced this
demonstrative case against the well-known
doctrine of Lamarck." - Origin, p. 242
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Complex outcomes of simple behavioral rules
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Chapter VIII Hybridism
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Chapter IX On the imperfections of the
geological record
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The Weald
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Chapter X On the geological succession of
organic beings
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Chapters XI-XII Geographical distribution
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Experiments on duck's feet
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Chapter XIII Mutual affinities of organic
beings morphology, embryology, rudimentary organs
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Chapter XIV Recapitulation and conclusion
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"I get by with a little help from my friends..."

• A one-man book group
• Blogging the Origin by John Whitfield
• http//scienceblogs.com/bloggingtheorigin

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Further reading
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The evidence for Darwin's Principle of
Divergence the world's first ecological
experiment
Sinclair 1816
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Nothing new under the sun the Biodiversity II
experiment