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History of evolutionary thought

  1. 1.  Definition - gradual change of a population over time  Types GEOLOGIC EVOLUTION -Hutton and Lyell BIOLOGICAL or ORGANIC EVOLUTION  The foundation of modern evolutionary thought was described by Charles Darwin
  2. 2. Greek Philosophers • Plato’s Idealism • Aristotle’s scala naturae (scale of nature)  special creation of each species  organisms were created in their current form  the earth was only a few thousand years old
  3. 3. CARL Von LINNE  Swedish botanist  worked on the classification of plants  published Species Plantarum (~7,300 plants)  ordered classification of plants based on their similarities  showed the natural relationships of plants
  4. 4. THOMAS MALTHUS  economist & clergyman  published An Essay on the Principle of Population  Populations had an inherent tendency to increase geometrically, while the resources needed to support this growth increase slowly or not at all.  Because of the continued growth of a species would outstrip needed resources, growth would be limited.
  5. 5. JEAN-BAPTISTE de LAMARCK  French biologist  proposed that modern species descended from other species  Lamarckism based on two theories: 1. Inheritance of Acquired Characteristics - traits acquired by an individual during its life are passed to its offspring 2. Use and Disuse - organs of the body that were used extensively to cope with the environment became larger and stronger, while organs that were not used deteriorated
  6. 6.  Tendency toward perfection  Behavior has no effect on heritable trait  BUT first to use scientific method in understanding evolution
  7. 7. THE ROAD TO EVOLUTIONARY THEORY Evolution Before Darwin Example: The Evolution of the Giraffe Giraffes obtained their long necks from previous giraffes who stretched to eat the leaves of high tree branches. Stretching increased the length of their necks, and this acquired characteristic was passed to the next generation.
  8. 8. Lamarckism  first to present a unified theory that attempted to explain the changes in organisms from one generation to the next  Although, mechanisms proposed for change was wrong, since acquired characteristics are not heritable!!!  origin of species from preexisting species  ability of organisms to adapt
  9. 9. GEORGES CUVIER  French anatomist and naturalist and writer  paleontologist  strongly opposed the concept of evolution  history of living organisms recorded in layers of rock containing a succession of fossil species in chronological order  fossils were organisms that had died in a series of catastrophes, after which extinct plants and animals were replaced by the immigration of distant species to the devastated region  Catastrophism
  10. 10. JAMES HUTTON  Scottish geologist  took up law, medicine and agriculture  published Theory of the Earth  geological change occurred slowly but continuously by the process of Gradualism  sedimentary rock that encased fossils formed by the gradual accumulation of sediments in bodies of water
  11. 11. GEORGES CUVIER JAMES HUTTON CHARLES LYELL Geological evolution  the earth is very old and constantly changing  life existed millions of years ago  geologists were convinced of an ancient earth, but were at odds over how to explain the appearance and disappearance of species in the fossil record  Believed in special creation
  12. 12. GREGOR MENDEL  Austrian biologist  discovered the basic principles of heredity  father of Classical Genetics  Individual characteristics determined by inherited factors transmitted from parent to offspring.
  13. 13. CHARLES DARWIN  voyage on the H.M.S. Beagle (1836)  published (1859) The Origin of Species  first person who proposed a mechanistic approach to evolutionary thought  the father of synthetic evolution
  14. 14.  Galapagos tortoise Darwin’s finches Most organisms on the islands were endemic.
  15. 15.  species not specially created in their present forms, but had evolved from ancestral species  proposed a mechanism for evolution: Natural Selection A population of organisms can change over time as a result of individuals with certain heritable characteristics leaving more offspring than other individuals.
  16. 16. ALFRED RUSSELL WALLACE  English naturalist  studied the Malay archipelago and Amazon  proposed a theory of evolution similar to Darwin’s “Then I saw at once that the ever-present variability of all living things would furnish the material from which, by the mere weeding out of those less adapted to the actual conditions, the fittest alone would continue the race.”
  17. 17. Darwinism in Historical Context
  18. 18. HUGO CARL ERICH VON DE VRIES CORRENS TSCHERMAK  rediscovered Mendel’s laws of heredity  the start of rediscovering evolution in terms of Mendel’s ideas
  19. 19. JAMES WATSON FRANCIS CRICK  elucidated the structure of DNA (genetic material)  DNA contains coded information which acts as a blueprint for the transfer of hereditary information from generation to generation  mutation as the raw material for evolution

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