evolution n.
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Evolution PowerPoint Presentation


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  1. Evolution By: Andrew George!!!!!! YAY!!!!!

  2. Evolution and the Nature of Science • Evolution is the theory that organisms change over time as a result of natural selection • Scientists estimate that the first fish-to-land transitional animals existed 375 million years ago • Paleontologists found fossils with primitive lungs as well as gills • In Canada a scientific expedition discovered the Tiktaalik which was a transitional animal

  3. Cont’d • This fish was found in Nunavut, near the Arctic circle in northern Canada • Evolution helps to understand how things are related • Differences in organisms genetics and experiences causes natural selection.

  4. Cont’d • When SARS broke out in China the virus was found to be evolved from a known type. • Antibiotics and bacteria • Guppies in streams are bigger • Guppies in rivers are smaller • Incremental evolution takes a long period of time. (subgroups & separation)

  5. Cont’d • Speciation can be the result of incremental evolution • Turtles have amniotic eggs • Reptiles split into dinosaurs and birds • Transition from reptiles to mammals showed larger brains, specialized organs, and movement of limbs under the body.

  6. Cont’d • For thousands of years people have been harvesting crops. By selecting the best grain to replant they modified the genetic structure of the plants • (artificial selection)

  7. Cont’d • Theory or fact? • Theory refers to a comprehensive explanation that is supported by a vast body of evidence • Fact is an observation, measurement, or other form of evidence

  8. Cont’d • Positions on Evolution are scientism, deism, and theism • Scientism- science is everything • Deism- God made it but doesn’t mess with it now • Theism- God made it and is still changing things around

  9. The Rise of Evolutionary Biology • “Nothing in biology maks sense except in the light of evolution” (Theodosius Dobzhansky) • “change over time via descent with modification” (Harrison, 2001) • The woodpecker was one of Darwin’s favorite examples of adaptation • (beak, tail, feet)

  10. Cont’d • The stages of evolution • Evolutionary and non-Evolutionary ideas before Darwin • Darwin’s theory(1859) • The eclipse of Darwin(1880-1920) • The modern synthesis (1920s to 1950s)

  11. Cont’d • Species fixity was a staple of Darwin’s time • Darwin’s grandfather Erasmus Darwin also discussed evolution • John Baptiste Lamarck and his theory of transformism

  12. Cont’d • Lamarck’s thoery • An internal force caused offspring to be slightly different from the parents • Inheritance of acquired characteristics also changed offspring (giraffes)

  13. Cont’d • Lamarck was wrong • He published Philosophie Zoologique • Georges Cuvier began the study of taxonomy • His major groups though modified are used today • Contrary to Lamarck he believed that species could go extinct

  14. Cont’d • Darwin traveled aboard a ship named the Beagle(1832-1837) • His father was a doctor • His father in law controlled the Wedgwood china business • Darwin did not label which island his various species came from

  15. Cont’d • Alfred Russel Wallace had arrived at a very similar idea to Darwin’s natural selection • Both ideas were announced at the Linnaean Society in London (1858) • After that Darwin wrote “On the Origin of Species”

  16. Cont’d • In Darwin’s theory evolution is not inherently or automatically progressive • There is not inherent tendency to rise to a higher form

  17. Cont’d • One objection to Darwin’s theory was that it lacked a good theory of heredity • “blending” • Red and white couple • Lamarckian theory was most popular theory of heredity

  18. Cont’d • German Biologist August Weismann produced strong evidence and theoretical arguments that acquired characteristics are not inherited • Erik Nordenskiold wrote “An influential history of biology” that questioned Darwin

  19. Cont’d • Gregor Mendel’s work was rediscovered • Mendelism became the generally accepted theory of heredity since the 1920’s • Early mendelians opposed Darwin’s theory of natural selection • They supported the theory that macromutations caused evolution

  20. Cont’d • The synthesis of Darwin’s thoery of natural selection with the Mendelian theory of heredity is known as neo-Darwinism • “The variation of Animals in Nature” was written by G.C. Robson and O.W. Richards • They accepted neither Mendelism or Darwinism • Argued that species are non-adaptive and have nothing to do with natural selection

  21. Cont’d • “The Material Basis of Evolution”, argued that speciation was produced by macromutations and not small variations • The changes in gene frequencies within a gene pool is evolution • Orthogenesis is straight line vs tree

  22. Summary of evolution • Evolution means decent with modification (tree) • Living things possess adaptations to their natural environment • Evolution was discussed prior to Darwin but fixity of species was the prevalent thought

  23. Summary Cont’d • Darwin explains change and adaptation through natural selection • Darwin’s peers accepted his idea of evolution but not his theory of natural selection • Darwin lacked a theory of heredity, Mendel’s work supported his later

  24. Summary Cont’d • Fisher, Haldane, and Wright demonstrated that Mendelian heredity and natural selection are compatible(neo-darwinism) • Neo-Darwinism spread through all areas of biology in the 1930’s and 40’s

  25. The Development of Evolutionary Theory • Greek Philosopher Anaxiamander • Roman philosopher Lucretius • They coined the concept that all living things were related and had changed over time • Carl Linn set up the hierarchical classification of animals

  26. Cont’d • Linnaean Structure was that each species or taxon belonged to a higher category • Georges-Luis Leclerc, Comte de Buffon proposed that species could change during the 18th century in a 44 volume history of all (then) known animals and plants

  27. Cont’d • William Smith developed the Principle of Biological Succession • Each period of earth history has it’s own fossil layer • Father of Stratigraphy

  28. Cont’d • Abraham Gottlob Werner and Baron Georges Cuvier were proponents of catastrophism • Proposed that there had been several creations and catastrophes in the history of earth • Only bacteria are able to incorporate non-genetic traits

  29. Darwin’s Theory • Adaptation: all organisms adapt to their environments • Variation: all organisms are variable in their traits • All organisms tend to over reproduce • Some organisms reproduce more that others (natural selection)

  30. Wallace-Darwin Theory • Individuals have different successes in reproducing • Left unchecked population tends to expand exponentially • Organisms best able to survive and reproduce will leave more offspring • Genes frequencies changing in the gene pool will cause the phenotype to change