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Evolution I 2007

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  • 1. Evolution I.
  • 2. EVOLUTION
    • gradual unfolding of new varieties of life from previous forms over long periods of time (Darwin)
    • from the genetic perspective : a change in allele frequency from one generation to the next
    • TWO KINDS OF EVOLUTION
      • microevolution – short term effects occuring over just a few generations
      • macroevolution – long-term effects through fossil history, large changes produced only after many generations
  • 3. Evolutional theories
  • 4. JEAN BAPTISTE LAMARCK (1744 – 1829)
    • Popularised the idea of evolution
    • First scientific evolution theory
    • Basic concepts of the Lamarck’s theory:
      • emphasis on the dynamic interaction of organic forms with the environment
      • environment affects and induce change in organic forms
      • acquired characteristic is passed through heredity to the next generations
  • 5. GEORGES CUVIER (1769 – 1832)
    • the „ father “ of zoology, palaeontology, and comparative anatomy
    • criticised Lamarck ’ s views on evolution
    • proposed theory of catastrophism:
      • series of violent and sudden catastrophes
      • all of creatures were destroyed during the catastrophe
      • after things settled down, areas were restocked with new organisms different from those previously living there)
  • 6. CHARLES DARWIN (1809 – 1882)
    • 1828 – 1831 theology studies (Christ’s College, Cambridge)
    • (Reverend John Stevens Henslow – lectures in botany)
    • 1831 – 1836 naturalist on a scientific expedition around the globe (H.M.S. Beagle) – recommended by Professor Henslow
    • 1842 – short summary of Darwin’s views on natural selection
    • 1859 – Darwin completed and published his work “ On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”
  • 7. Charles Darwin stopover at the Galápagos Islands – Darwin described 13 species of finches resembled one another in the structure of their beaks, body forms, and plumage
  • 8. Darwin´s finches
  • 9. DARWIN’S CONCEPT OF EVOLUTION
    • All species are capable of producing offspring faster than the food supply increases.
    • All living things show variation; no two individuals of a species are exactly alike.
    • Because there are more individuals than can possibly survive, there is a fierce struggle for existence and those with a favourable variation in characteristics are necessary for survival will possess an advantage over others.
    • These favourable variations are inherited and passed on to the next variation.
    • Over long periods of geologic time, these successful variations produce great differences that result in new species.
    • The background of the process is natural selection.
  • 10. The fate of the Darwin's theory
  • 11. Alfred Russel Wallace (1823 – 1913)
    • 1855 –published an article concerning the succession of species and their mutability
  • 12. NEODARWINISM - THE MODERN SYNTHESIS
    • Evolution is defined as a two stage process :
      • Production and redistribution of variation (inherited differences between individuals)
      • Natural selection acts on this variation (inherited differences, or variation, among individuals differentially affect their ability to reproduce successfully
  • 13. RECENT CHALLENGES TO THE MODERN SYNTHESIS
    • neutral mutations
      • Much of variation in natural population is due to neutral mutations and chance factors (i.e. genetic drift).
      • Neutral mutations are not controlled by natural selection.
      • “ Natural selection is the editor, rather than composer of genetic message” (King and Jukes 1969)
    • gradualism X punctuationalism
      • gradualism – evolution changes accumulate gradually in evolving lineages
      • punctuationalism (punctuated equilibrium) – evolution is nongradual process, evolutionary rates are not constant, the evolution is a process of long stasis and sudden quick spurts
  • 14. MECHANISMS OF EVOLUTION
    • Factors that produce and redistribute variation
      • mutation
      • migration
      • genetic drift
      • recombination
    • Natural selection
      • differential net reproductive success
      • Some of genetic variations among individual within a population may influence reproductive success. Therefore some individuals contribute more offspring to succeeding generations.
  • 15. Theodosius Dobzhansky (1900 – 1975) "Nothing in biology makes sense except in the light of evolution."
  • 16. http://www.pbs.org/wgbh/evolution/index.html Public Broadcasting Service – www section about evolution
  • 17. EARLY EVOLUTIONARY HISTORY
    • The origin of Earth
      • 4,5 – 4,6 thousands million years ago
    • The oldest fossils were found in 3,8 thousands million years old sedimentary rocks from Greenland (the oldest terrestrial rocks).
  • 18. Prebiotic evolution
  • 19. What happened during the prebiotic evolution? Urey-Miller experiment
  • 20. The Urey - Miller experiment
  • 21. The theory of RNA world nucleotides RNA aminoacids, proteins DNA
  • 22. GEOLOGIC PERIODS PROTEROZOI C ARCHA EAN PREKAMBRI AN Origin of life Recent QUARTERNARY TERTIARY C ENOZOI C ERA MESOZOIC P ALEOZOIC
  • 23. Geologic periods
  • 24. The Precambrian's lower limit is not defined, but ended about 542 (570?) million years ago. The Precambrian encompasses about 90% of Earth's history.
  • 25. EARLY EVOLUTIONARY HISTORY II.
    • Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia.
    • They ha ve been dated at 3,5 thousands million years.
  • 26. Ediacara Hills - Australia Tribrachidium Charniodiscus Mawsonites Dickinsonia Fossils of precambrian soft-bodied organisms
  • 27. Ediacaran (Vendian) organisms – possible reconstruction
  • 28. Riddle of Ediacara
  • 29. Cambrian – beginning of Paleozoic
  • 30. Pikaia – a fossil of the first chordate
  • 31. Pikaia – reconstruction
  • 32. Cambrian explosion (cambrian radiation)
  • 33. At the end of Paleozoic first land vertebrates appeared reptile Dimetrodon
  • 34. Mass extinction at the end of Permian 90% of species extinct
  • 35. http://www.pbs.org/wgbh/evolution/change/deeptime/index.html Evolution of life
  • 36. http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/index.html What happened before 65 millions of year s ? K/T border (= cretaceous / tertiary) – extinction of dinosaurs and a lot of other species (approximately 75 % of species)