Evolution Practicals
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Evolution Practicals

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Evolution Practicals Evolution Practicals Presentation Transcript

  • Evolution - practicals
  • http://www.pbs.org/wgbh/evolution/index.html Public Broadcasting Service – www section about evolution
  • 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
  • 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).
    • Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia. They has been dated at 3,5 thousands million years.
  • 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.
  • Ediacara Hills - Australia Tribrachidium Charniodiscus Mawsonites Dickinsonia Fossils of precambrian soft-bodied organisms
  • Ediacaran (Vendian) organisms – possible reconstruction
  • Riddle of Ediacara
  • Cambrian – beginning of Paleozoic
  • Pikaia – a fossil of the first chordate
  • Pikaia – reconstruction
  • Cambrian explosion (cambrian radiation)
  • At the end of Paleozoic first land vertebrates appeared reptile Dimetrodon
  • Mass extinction at the end of Permian 90% of species extinct
  • http://www.pbs.org/wgbh/evolution/change/deeptime/index.html Evolution of life
  • 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)
  • Evolutional theories
  • 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
  • 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)
  • 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”
  • 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
  • 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.
  • The fate of the Darwin's theory
  • Alfred Russel Wallace (1823 – 1913)
    • 1855 –published an article concerning the succession of species and their mutability
  • 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
  • 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
  • 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.
  • Theodosius Dobzhansky (1900 – 1975) "Nothing in biology makes sense except in the light of evolution."