Transcript Darwin`s Theory of Evolution

Darwin and Evolutionary Biology
NASC 120
Darwin on HMS Beagle 1831-1836
http://darwin-online.org.uk/
Captain Robert Fitzroy
Galapagos Islands
Establishing a respectable career
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1838-43
Zoology of the Voyage of H.M.S. Beagle (5 parts)
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1839
Journal of Researches (Voyage of the Beagle)
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1842
The Structure and Distribution of Coral Reefs
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1844
Geological Observations of Volcanic Islands
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1846
Geological Observations of South America
Establishing a respectable career
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1838-43
Zoology of the Voyage of H.M.S. Beagle (5 parts)
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1839
Journal of Researches (Voyage of the Beagle)
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1842
The Structure and Distribution of Coral Reefs
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1844
Geological Observations of Volcanic Islands
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1846
Geological Observations of South America
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1851-54
Monograph on Cirripedia (Barnacles) 4 vols.
http://darwin-online.org.uk/EditorialIntroductions/Richmond_cirripedia.html
Lippson, A.J. & Lippson, R.L. 1984. Life in the
Chesapeake Bay. Johns Hopkins University Press.
Barnacles: anatomy, morphology, taxonomy, developmental
history
http://www.hps.cam.ac.uk/whipple/explore/microscopes/darwinsmicroscopes/
Establishing a respectable career
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1838-43
Zoology of the Voyage of H.M.S. Beagle (5 parts)
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1839
Journal of Researches (Voyage of the Beagle)
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1842
The Structure and Distribution of Coral Reefs
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1844
Geological Observations of Volcanic Islands
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1846
Geological Observations of South America
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1851-54
Monograph on Cirripedia (Barnacles) 4 vols.
all the while being more and more convinced of a heresy…Transmutation
Erasmus Darwin (1731-1802)
1794
Jean Baptiste de Lamarck (1744-1829)
1809
Robert Chambers (1802-1871)
• Vestiges of the History of Natural
Creation (1844), Anonymous
• ‘A Victorian Sensation’
Secord (2001)
http://pages.britishlibrary.net/phrenology/images/ch
ambers.jpg
Herbert Spencer (1820-1903)
“The Development
Hypothesis” (1852)
“Progress: Its law and
cause” (1857)
Darwin’s Observations
• 1) Geographic distribution of species
• 2) Fossil assemblage of South America
• 3) flora and fauna of the Galapagos Islands
Geographic distribution
• Species are not uniformly spread over
different regions and climates – similar species
appear ‘clumped’ in specific regions
– Especially noticeable where there is geographic
isolation; e.g. islands and mountain ranges
– Could environment be molding organisms to fit
local conditions?
Mt Ararat
Wallace Line
Galapagos Islands
• Hypothesis 1: Noah’s Ark
– Distribution of flora and fauna from central
location in Turkey
• Hypothesis 2: Evolution and adaptation to
new locales and changing geological
formations (islands, mountain ranges etc.)
Establishing a respectable career
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1838-43
Zoology of the Voyage of H.M.S. Beagle (5 parts)
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1839
Journal of Researches (Voyage of the Beagle)
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1842
The Structure and Distribution of Coral Reefs
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1844
Geological Observations of Volcanic Islands
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1846
Geological Observations of South America
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1851-54
Monograph on Cirripedia (Barnacles) 4 vols.
Working on a big book, ‘Natural Selection’, when suddenly…
Alfred Russel Wallace (1823-1913)
“On the tendency of varieties to depart indefinitely from the
original type” (1858)
Darwin’s Key Supporters
Lyell (1797-1875)
Hooker (1817-1911)
Huxley (1825-1895)
Darwin
http://darwin-online.org.uk/
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Nov. 24, 1859 1st edition
1860 2nd ed.
1861 3rd ed.
1866 4th ed.
1869 5th ed.
1872 6th ed.
1876 6th ed. with
additions and
corrections (final
version)
http://darwin-online.org.uk/
The Origin of Species
• 1) – amasses a large and diverse amount of
evidence that evolution (transmutation)
occurs – “descent with modification”
• 2) – provides a naturalistic & materialistic
mechanism of how it occurs
– Natural selection
Descent with modification
• All species of plant and animals (etc.) derived
from a common ancestral primitive form of
life, modifying, diversifying over great lengths
of time as environment changes
• Short argument:
• Competition + random variation + natural
selection  evolution (species change)
Darwin’s argument: the long form
• 1. Malthusian Reproduction – more organisms are produced than available
resources can support
• 2. This results in a competition for resources (food, space, mates, sunlight
etc.)
• 3. There is a natural variability of traits in any population (no two
organisms exactly alike)
– This variation is ‘random’, i.e. not directed or aiming at anything – nonteleological
• 4. Some traits are better adapted (more fit) to the local environment
• 5. 2 + 4  some individuals have a competitive edge over others (they will
reproduce in greater numbers)
• 6. Organisms pass on traits to their offspring (Inheritance)
• 7. This results in more of the adaptive traits being passed on in next
generation (Natural selection for more adaptive traits)  Evolution –a
change in the frequency of certain traits in a population (microevolution)
• 8. Over great lengths of time this micro evolutionary change will
accumulate into large macro-evolutionary changes, resulting in the origin
of new species
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Zoology of the Voyage of H.M.S. Beagle
Voyage of the Beagle
The Structure and Distribution of Coral Reefs
Geological Observations of Volcanic Islands
Geological Observations of South America
Monograph on Cirripedia (Barnacles) 4 vols.
On the Origin of Species by Means of Natural Selection, or the Preservation
of Favoured Races in the Struggle for Life
On the Various Contrivances by which British and Foreign Orchids are
Fertilised by Insects
Variation of Animals and Plants Under Domestication
The Descent of Man, and Selection in Relation to Sex
The Expression of Emotions in Man and Animals
Movement and Habits of Climbing Plants
Insectivorous Plants
The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom
The Different Forms of Flowers on Plants of the Same Species
The Life of Erasmus Darwin
The Power of Movement in Plants
The Formation of Vegetable Mould Through the Action of Worms
Speciation
Darwinian Evolution:
a two-step process
1. Random (non-directed) variation of traits in a
population
2. Selection by environment for adaptive or
favourable ranges of this naturally occurring
variation
The Species Problem
• Problem of Diversity: Why so many species?
– Adaptive radiation to fill available niches,
divergence and adaptation by natural selection
• Problem of Homology: Why so many
similarities?
– Descent from a common ancestor (species look related
because they really are)
• Problem of Adaptedness: Why do organisms
appear so well designed for their
environments and ways of life?
– Natural selection weeds out non-adaptive traits,
favours adaptive traits