2. http://www.pbs.org/wgbh/evolution/index.html Public Broadcasting Service www section about evolution 3. EVOLUTION
- gradual unfolding of new varieties of life from previous forms over long periods of time (Darwin)
- from the genetic perspective : achange in allele frequency from one generation to the next
- microevolution short term effects occuring over just a few generations
- macroevolution long-term effects through fossil history, large changes produced only after many generations
4. EARLY EVOLUTIONARY HISTORY
- 4,5 4,6 thousands million yearsago
- The oldest fossils were found in 3,8thousands 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 3,5thousands million years.
5. EARLY EVOLUTIONARY HISTORYII.
- Earliest known structurally preserved organisms are stromatolites found near the North Pole, Australia.
- They ha vebeen dated at 3,5thousands million years.
6. Ediacara Hills - Australia Tribrachidium Charniodiscus Mawsonites Dickinsonia Fossils of precambrian soft-bodied organisms 7. Ediacaran (Vendian) organisms possible reconstruction 8. Riddle of Ediacara 9. Cambrian beginning of Paleozoic 10. Pikaia a fossil of the first chordate 11. Pikaia reconstruction 12. Cambrian explosion (cambrian radiation) 13. At the end of Paleozoic first land vertebrates appeared reptileDimetrodon 14. Mass extinction at the end of Permian 90% of species extinct 15. http://www.pbs.org/wgbh/evolution/change/deeptime/index.html Evolution of life 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. Evolutionaltheories 18. JEAN BAPTISTE LAMARCK(1744 1829)
- Popularised the idea of evolution
- First scientific evolution theory
- Basic concepts of the Lamarcks 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
19. 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)
20. CHARLES DARWIN (1809 1882)
- 1828 1831 theology studies (Christs 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 Darwins views on natural selection
- 1859 Darwin completed and published his work On the Origin of Speciesby means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life
21. Charles Darwin stopover at the Galpagos Islands Darwin described 13 species of finches resembled one another in the structure of their beaks, body forms, and plumage 22. DARWINS 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.
23. The fate of the Darwin's theory 24. Alfred Russel Wallace(1823 1913)
- 1855 published an article concerning the succession of species and their mutability
25. 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
26. RECENT CHALLENGES TOTHEMODERNSYNTHESIS
- 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
27. MECHANISMS OF EVOLUTION
- Factors that produce and redistributevariation
- 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.
28. Theodosius Dobzhansky(1900 1975) "Nothing in biology makes sense except in the light of evolution."