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Evolution and Natural Selection

Evolution and Natural Selection. Evolution. “Nothing in biology makes sense except in the light of evolution” Theodosius Dobzhansky. Evolution. Evolvere “to unfold or unroll” Central organizing concept of how the world and organism have come to function Builds on accumulating knowledge

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Evolution and Natural Selection

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  1. Evolution and Natural Selection

  2. Evolution “Nothing in biology makes sense except in the light of evolution” Theodosius Dobzhansky

  3. Evolution • Evolvere • “to unfold or unroll” • Central organizing concept of how the world and organism have come to function • Builds on accumulating knowledge • Need organisms history to fully understand it • Descent with modification • Often with diversification

  4. Evolution • Genetic change in a population or species over generations; heritable changes that have produced Earth’s diversity of organisms

  5. Before there was Darwin…

  6. Anaximander • 16th Cent BC

  7. Living creatures formed from water

  8. Humans and animals descended from fish Interpreted observations of Sharks/dogfish as intermediaries between fish and land animals

  9. History of Evolutionary thought

  10. Plato 427-347 BC • Essentialism • Essence- perfect form • Earthly plane & essential plane • Static world • Variation • Imperfect earthly representation • Only essence matters

  11. Aristotle 384- 322 B.C

  12. Aristotle 384- 322 B.C • Essentialism with taxonomical organization • Scala Naturae • Aka Scale of nature • Aka ladder of nature • God created all species • No gradation among species • No new species, no extinctions • Spontaneous generation

  13. Scala Naturae

  14. …….Add Judeo-christianity

  15. Historical Time Frame • Plato/ Aristotle • Essentialism- fixed species • Victorian era- 1700-1800 • “Pre- science” • Natural Theology- Life’s diversity attributed to god’s splendor • God created all diversity • Earth very young • Role of science to catalogue god’s creatures • “god’s splendor in the intricacies of life” • Taxonomy

  16. Victorian Era • Victorian era • Conservative, chaste • Lack in education • Lack in communication • Christianity dominated • Earth created in 7 days • Earth is not old 6000 yrs • Earth is static

  17. Newton 1643- 1727 • Explained physical phenomena • Introduced Mechanistic ideology • Explain the world outside of god • Introduced the power of reason • Beginnings of an atmosphere that encouraged the questioning of old beliefs • Spurred the “Age of Enlightenment” • Faith in progress & the power of reason

  18. Cuvier 1769-1832 • Paleontology, geology, comparative anatomy • History of life documented via fossils • Older fossils deeper • Unique species at each depth • Extinction via catastrophism • Form & function • No evolution • So complex could not be altered

  19. James Hutton 1726-1797 • Father of Geology • Earth is OLD • “no vestige of a beginning, no prospect of an end” • Older than 6000 yrs • Processes of earths changes can be explained by present time processes • Ex water • Gradualism • Profound change is the cumulative product of slow continuous processes

  20. Charles Lyell • Geologist • Principles of Geology • Earth is very old • Uniformitarianism • Geological processes have not changed over time- same rate today as in past • Responsible for timeline of earth

  21. Thomas Malthus 1776- 1834 • Economist, Population study • “Essays on the principle of population” 1798 • Populations grow faster than food supply • Not all survive….struggle for life

  22. Jean Baptiste Lamarck • First to propose Evolution • Proposed idea adaptation • Inheritance of acquired characteristics • Introduced mechanism of evolution • Use and disuse • Incorrect mechanism • Ridiculed

  23. Evolution was in the air… • Mechanistic thinking (Newton) • Timeline- earth old (Hutton & Lyell) • Fossil evidence (Cuvier) • Relatedness amongst species- descent via inheritance of characteristics over time (Lamark, buffon) • Adaptation to environment (Lamark) • Struggle for existence (Malthus) • BUT natural theology is still prevalent

  24. Darwin

  25. Voyage of the Beagle, 1831

  26. Similar Solutions • Adaptation • Trait that aids in the survival or reproduction of an organism

  27. Fossils

  28. Galapagos

  29. Darwin • Perspective • Time to read • Specimens survive

  30. Artificial Selection • Intentional breeding for certain traits

  31. Darwin’s Observations • Diversity • Similar solutions- ie adaptations • Fossils • Geographic distribution • Environment influences distribution of plants & animals • Read & incorporated the work of others • Malthus- population • Lyell- earth old • Artificial selection

  32. Darwin • The origin of species • “on the origin of species by means of natural selection, or the preservation of favored races in the struggle for life” • Descent with modification • Theory of natural selection

  33. Wallace 1823-1913 • Naturalist • Father of Biogeography • “on the tendency of varieties to depart indefinitely from the original type” • Independently conceived natural selection • Not so lucky

  34. Origin of Species • Descent with modification • Aka evolution • All organisms related through descent from some unknown ancestor • Happened over long periods of time • Adapt to environment • Well accepted within 15 years- timing • Differential reproductive success • More offspring than can survive will be produced • Struggle to survive • Variation among individuals • Best suited for the environment will survive • Aka Natural selection

  35. What was Darwin Missing? • Mechanism of inheritance • Hershey & Chase 1952 • Linked DNA to inheritance • Direct evidence for natural selection • Grant & Grant 1972-2003 • Darwin’s finches in Galapagos

  36. MUST Have for Natural Selection to occur • Individual variation must exist • Variation must be heritable • More offspring produced than can survive • Limited resource- selective pressure

  37. Evolution….After Darwin…

  38. Evidence of Evolution • Fossil record • Biogeography • Comparative anatomy • Comparative embryology/ development • Comparative behavior • Molecular biology

  39. Fossils • Fossil any preserved remnant or impression of an organism that lived in the past • http://www.youtube.com/watch?v=VtWdUG4nNCU • http://www.youtube.com/watch?v=34eKAm48LfM

  40. Biogeography • Study of geographic distribution • Use to study how lineages of animals evolved

  41. Comparative Anatomy • Comparison of body structures among taxa to understand evolutionary relationships/ history • Homologous vs analogous

  42. Homologous Structures • A characteristic shared by 2 or more taxa that evolved from the same structure in their common ancestor

  43. Analogous Structures • Analogous structures have a similar function but DO NOT share common ancestry

  44. Comparative Embryology • Compare developmental patterns (ontology) to understand common ancestry

  45. Comparative Behavior • Compare behavior to understand common ancestry

  46. Molecular biology • Study of DNA sequences to understand evolutionary relationships • Revolutionized our understanding of evolutionary biology

  47. Modern Synthesis • Modern view of our understanding of evolution • A comprehensive theory of evolution emphasizing natural selection, gradualism, and populations as the fundamental units of evolutionary change • New Terms • Evolution= slow accumulation of change over time • Mechanism of change= natural selection • Editing • Evolutionary adaptation

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