Evolution Practicals


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Evolution Practicals

  1. 1. Evolution - practicals
  2. 2. http://www.pbs.org/wgbh/evolution/index.html Public Broadcasting Service – www section about evolution
  3. 3. EVOLUTION <ul><li>gradual unfolding of new varieties of life from previous forms over long periods of time (Darwin) </li></ul><ul><li>from the genetic perspective : a change in allele frequency from one generation to the next </li></ul><ul><li>TWO KINDS OF EVOLUTION </li></ul><ul><ul><li>microevolution – short term effects occuring over just a few generations </li></ul></ul><ul><ul><li>macroevolution – long-term effects through fossil history, large changes produced only after many generations </li></ul></ul>
  4. 4. EARLY EVOLUTIONARY HISTORY <ul><li>The origin of Earth </li></ul><ul><ul><li>4,5 – 4,6 thousands million years ago </li></ul></ul><ul><li>The oldest fossils were found in 3,8 thousands million years old sedimentary rocks from Greenland (the oldest terrestrial rocks). </li></ul><ul><li>Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia. They has been dated at 3,5 thousands million years. </li></ul>
  5. 5. EARLY EVOLUTIONARY HISTORY II. <ul><li>Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia. </li></ul><ul><li>They ha ve been dated at 3,5 thousands million years. </li></ul>
  6. 6. Ediacara Hills - Australia Tribrachidium Charniodiscus Mawsonites Dickinsonia Fossils of precambrian soft-bodied organisms
  7. 7. Ediacaran (Vendian) organisms – possible reconstruction
  8. 8. Riddle of Ediacara
  9. 9. Cambrian – beginning of Paleozoic
  10. 10. Pikaia – a fossil of the first chordate
  11. 11. Pikaia – reconstruction
  12. 12. Cambrian explosion (cambrian radiation)
  13. 13. At the end of Paleozoic first land vertebrates appeared reptile Dimetrodon
  14. 14. Mass extinction at the end of Permian 90% of species extinct
  15. 15. http://www.pbs.org/wgbh/evolution/change/deeptime/index.html Evolution of life
  16. 16. 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)
  17. 17. Evolutional theories
  18. 18. JEAN BAPTISTE LAMARCK (1744 – 1829) <ul><li>Popularised the idea of evolution </li></ul><ul><li>First scientific evolution theory </li></ul><ul><li>Basic concepts of the Lamarck’s theory: </li></ul><ul><ul><li>emphasis on the dynamic interaction of organic forms with the environment </li></ul></ul><ul><ul><li>environment affects and induce change in organic forms </li></ul></ul><ul><ul><li>acquired characteristic is passed through heredity to the next generations </li></ul></ul>
  19. 19. GEORGES CUVIER (1769 – 1832) <ul><li>the „ father “ of zoology, palaeontology, and comparative anatomy </li></ul><ul><li>criticised Lamarck ’ s views on evolution </li></ul><ul><li>proposed theory of catastrophism: </li></ul><ul><ul><li>series of violent and sudden catastrophes </li></ul></ul><ul><ul><li>all of creatures were destroyed during the catastrophe </li></ul></ul><ul><ul><li>after things settled down, areas were restocked with new organisms different from those previously living there) </li></ul></ul>
  20. 20. CHARLES DARWIN (1809 – 1882) <ul><li>1828 – 1831 theology studies (Christ’s College, Cambridge) </li></ul><ul><li>(Reverend John Stevens Henslow – lectures in botany) </li></ul><ul><li>1831 – 1836 naturalist on a scientific expedition around the globe (H.M.S. Beagle) – recommended by Professor Henslow </li></ul><ul><li>1842 – short summary of Darwin’s views on natural selection </li></ul><ul><li>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” </li></ul>
  21. 21. 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
  22. 22. DARWIN’S CONCEPT OF EVOLUTION <ul><li>All species are capable of producing offspring faster than the food supply increases. </li></ul><ul><li>All living things show variation; no two individuals of a species are exactly alike. </li></ul><ul><li>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. </li></ul><ul><li>These favourable variations are inherited and passed on to the next variation. </li></ul><ul><li>Over long periods of geologic time, these successful variations produce great differences that result in new species. </li></ul><ul><li>The background of the process is natural selection. </li></ul>
  23. 23. The fate of the Darwin's theory
  24. 24. Alfred Russel Wallace (1823 – 1913) <ul><li>1855 –published an article concerning the succession of species and their mutability </li></ul>
  25. 25. NEODARWINISM - THE MODERN SYNTHESIS <ul><li>Evolution is defined as a two stage process : </li></ul><ul><ul><li>Production and redistribution of variation (inherited differences between individuals) </li></ul></ul><ul><ul><li>Natural selection acts on this variation (inherited differences, or variation, among individuals differentially affect their ability to reproduce successfully </li></ul></ul>
  26. 26. RECENT CHALLENGES TO THE MODERN SYNTHESIS <ul><li>neutral mutations </li></ul><ul><ul><li>Much of variation in natural population is due to neutral mutations and chance factors (i.e. genetic drift). </li></ul></ul><ul><ul><li>Neutral mutations are not controlled by natural selection. </li></ul></ul><ul><ul><li>“ Natural selection is the editor, rather than composer of genetic message” (King and Jukes 1969) </li></ul></ul><ul><li>gradualism X punctuationalism </li></ul><ul><ul><li>gradualism – evolution changes accumulate gradually in evolving lineages </li></ul></ul><ul><ul><li>punctuationalism (punctuated equilibrium) – evolution is nongradual process, evolutionary rates are not constant, the evolution is a process of long stasis and sudden quick spurts </li></ul></ul>
  27. 27. MECHANISMS OF EVOLUTION <ul><li>Factors that produce and redistribute variation </li></ul><ul><ul><li>mutation </li></ul></ul><ul><ul><li>migration </li></ul></ul><ul><ul><li>genetic drift </li></ul></ul><ul><ul><li>recombination </li></ul></ul><ul><li>Natural selection </li></ul><ul><ul><li>differential net reproductive success </li></ul></ul><ul><ul><li>Some of genetic variations among individual within a population may influence reproductive success. Therefore some individuals contribute more offspring to succeeding generations. </li></ul></ul>
  28. 28. Theodosius Dobzhansky (1900 – 1975) &quot;Nothing in biology makes sense except in the light of evolution.&quot;