Evolution I 2007
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Evolution I 2007

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    Evolution I 2007 Evolution I 2007 Presentation Transcript

    • Evolution I.
    • 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
    • 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 finches
    • 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."
    • http://www.pbs.org/wgbh/evolution/index.html Public Broadcasting Service – www section about evolution
    • 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).
    • Prebiotic evolution
    • What happened during the prebiotic evolution? Urey-Miller experiment
    • The Urey - Miller experiment
    • The theory of RNA world nucleotides RNA aminoacids, proteins DNA
    • GEOLOGIC PERIODS PROTEROZOI C ARCHA EAN PREKAMBRI AN Origin of life Recent QUARTERNARY TERTIARY C ENOZOI C ERA MESOZOIC P ALEOZOIC
    • Geologic periods
    • 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.
    • 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)