Evolution

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Evolution

• By Andrew George!!!!!!
• YAY!!!!!

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Evolution and the Nature of Science

• Evolution is the theory that organisms change
  over time as a result of natural selection
• Scientists estimate that the first fish-to-land
  transitional animals existed 375 million years
  ago
• Paleontologists found fossils with primitive
  lungs as well as gills
• In Canada a scientific expedition discovered the
  Tiktaalik which was a transitional animal

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Contd

• This fish was found in Nunavut, near the Arctic
  circle in northern Canada
• Evolution helps to understand how things are
  related
• Differences in organisms genetics and experiences
  causes natural selection.

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Contd

• When SARS broke out in China the virus was found
  to be evolved from a known type.
• Antibiotics and bacteria
• Guppies in streams are bigger
• Guppies in rivers are smaller
• Incremental evolution takes a long period of
  time. (subgroups separation)

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Contd

• Speciation can be the result of incremental
  evolution
• Turtles have amniotic eggs
• Reptiles split into dinosaurs and birds
• Transition from reptiles to mammals showed larger
  brains, specialized organs, and movement of limbs
  under the body.

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Contd

• For thousands of years people have been
  harvesting crops. By selecting the best grain to
  replant they modified the genetic structure of
  the plants
• (artificial selection)

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Contd

• Theory or fact?
• Theory refers to a comprehensive explanation that
  is supported by a vast body of evidence
• Fact is an observation, measurement, or other
  form of evidence

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Contd

• Positions on Evolution are scientism, deism, and
  theism
• Scientism- science is everything
• Deism- God made it but doesnt mess with it now
• Theism- God made it and is still changing things
  around

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The Rise of Evolutionary Biology

• Nothing in biology maks sense except in the
  light of evolution (Theodosius Dobzhansky)
• change over time via descent with modification
  (Harrison, 2001)
• The woodpecker was one of Darwins favorite
  examples of adaptation
• (beak, tail, feet)

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Contd

• The stages of evolution
• Evolutionary and non-Evolutionary ideas before
  Darwin
• Darwins theory(1859)
• The eclipse of Darwin(1880-1920)
• The modern synthesis (1920s to 1950s)

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Contd

• Species fixity was a staple of Darwins time
• Darwins grandfather Erasmus Darwin also
  discussed evolution
• John Baptiste Lamarck and his theory of
  transformism

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Contd

• Lamarcks thoery
• An internal force caused offspring to be slightly
  different from the parents
• Inheritance of acquired characteristics also
  changed offspring (giraffes)

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Contd

• Lamarck was wrong
• He published Philosophie Zoologique
• Georges Cuvier began the study of taxonomy
• His major groups though modified are used today
• Contrary to Lamarck he believed that species
  could go extinct

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Contd

• Darwin traveled aboard a ship named the
  Beagle(1832-1837)
• His father was a doctor
• His father in law controlled the Wedgwood china
  business
• Darwin did not label which island his various
  species came from

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Contd

• Alfred Russel Wallace had arrived at a very
  similar idea to Darwins natural selection
• Both ideas were announced at the Linnaean Society
  in London (1858)
• After that Darwin wrote On the Origin of Species

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Contd

• In Darwins theory evolution is not inherently or
  automatically progressive
• There is not inherent tendency to rise to a
  higher form

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Contd

• One objection to Darwins theory was that it
  lacked a good theory of heredity
• blending
• Red and white couple
• Lamarckian theory was most popular theory of
  heredity

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Contd

• German Biologist August Weismann produced strong
  evidence and theoretical arguments that acquired
  characteristics are not inherited
• Erik Nordenskiold wrote An influential history
  of biology that questioned Darwin

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Contd

• Gregor Mendels work was rediscovered
• Mendelism became the generally accepted theory of
  heredity since the 1920s
• Early mendelians opposed Darwins theory of
  natural selection
• They supported the theory that macromutations
  caused evolution

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Contd

• The synthesis of Darwins thoery of natural
  selection with the Mendelian theory of heredity
  is known as neo-Darwinism
• The variation of Animals in Nature was written
  by G.C. Robson and O.W. Richards
• They accepted neither Mendelism or Darwinism
• Argued that species are non-adaptive and have
  nothing to do with natural selection

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Contd

• The Material Basis of Evolution, argued that
  speciation was produced by macromutations and not
  small variations
• The changes in gene frequencies within a gene
  pool is evolution
• Orthogenesis is straight line vs tree

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Summary of evolution

• Evolution means decent with modification (tree)
• Living things possess adaptations to their
  natural environment
• Evolution was discussed prior to Darwin but
  fixity of species was the prevalent thought

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Summary Contd

• Darwin explains change and adaptation through
  natural selection
• Darwins peers accepted his idea of evolution but
  not his theory of natural selection
• Darwin lacked a theory of heredity, Mendels work
  supported his later

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Summary Contd

• Fisher, Haldane, and Wright demonstrated that
  Mendelian heredity and natural selection are
  compatible(neo-darwinism)
• Neo-Darwinism spread through all areas of biology
  in the 1930s and 40s

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The Development of Evolutionary Theory

• Greek Philosopher Anaxiamander
• Roman philosopher Lucretius
• They coined the concept that all living things
  were related and had changed over time
• Carl Linn set up the hierarchical classification
  of animals

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Contd

• Linnaean Structure was that each species or taxon
  belonged to a higher category
• Georges-Luis Leclerc, Comte de Buffon proposed
  that species could change during the 18th century
  in a 44 volume history of all (then) known
  animals and plants

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Contd

• William Smith developed the Principle of
  Biological Succession
• Each period of earth history has its own fossil
  layer
• Father of Stratigraphy

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Contd

• Abraham Gottlob Werner and Baron Georges Cuvier
  were proponents of catastrophism
• Proposed that there had been several creations
  and catastrophes in the history of earth
• Only bacteria are able to incorporate non-genetic
  traits

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Darwins Theory

• Adaptation all organisms adapt to their
  environments
• Variation all organisms are variable in their
  traits
• All organisms tend to over reproduce
• Some organisms reproduce more that others
  (natural selection)

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Wallace-Darwin Theory

• Individuals have different successes in
  reproducing
• Left unchecked population tends to expand
  exponentially
• Organisms best able to survive and reproduce will
  leave more offspring
• Genes frequencies changing in the gene pool will
  cause the phenotype to change