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biology.lsu/webfac/kharms/BIOL1202Fall2007.htm

biology.lsu/webfac/kharms/BIOL1202Fall2007.htm

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  1. BIOL 1202, Section 1 Dr. Kyle Harms Course website: http://www.biology.lsu.edu/webfac/kharms/BIOL1202Fall2007.htm http://www.biology.lsu.edu/webfac/kharms/BIOL1202Fall2007.htm

  2. In BIOL 1202, good attendance pays off! Proportion of students Final exam score

  3. Chapter 22 Descent with Modification: A Darwinian View of Life

  4. Why are there so many species?

  5. The Theory of Evolutionby Natural SelectionCharles Darwin

  6. Hypothesis vs. Theory

  7. Hypothesis Tentative explanation of observations Educated guess

  8. Theory General explanation of important natural phenomena, developed through extensive & reproducible observations & experiments

  9. Western Historical Context Species are permanent, perfect, immutable Aristotle (384-322 B.C.) – Greek philosopher Dominant world view for > 2000 yr See timeline Fig. 22.2

  10. Western Historical Context A.D. – Natural Theology (Creationism) Species are permanent, perfect, immutable See timeline Fig. 22.2

  11. Western Historical Context Carolus Linnaeus (1707-1778) Swedish physician & botanist whose passion was taxonomy Developed a hierarchical classification scheme & binomial nomenclature See timeline Fig. 22.2

  12. Western Historical Context Carolus Linnaeus (1707-1778) Canis = genus lupus = specific epithet that refers to one species in the genusCanis The binomial is always italicized or underlined, the genus name is always capitalized, and the specific epithet is always lower case “King Philip Came Over For Gumbo Sunday” See Fig. 25.8

  13. Western Historical Context Georges Cuvier (1769-1832) French anatomist who largely developed paleontology, the study of fossils See timeline Fig. 22.2

  14. Western Historical Context Georges Cuvier (1769-1832) Deeper strata contain older taxa See timeline Fig. 22.2

  15. Western Historical Context Georges Cuvier (1769-1832) Preferred hypothesis for profound geologic change = catastrophism See timeline Fig. 22.2

  16. Western Historical Context James Hutton (1726-1797) Scottish geologist who offered an alternative to catastrophism Preferred hypothesis for profound geologic change = gradualism See timeline Fig. 22.2

  17. Western Historical Context Charles Lyell (1797-1875) Scottish geologist who incorporated Hutton’s gradualism into the theory of uniformitarianism See timeline Fig. 22.2

  18. Western Historical Context Charles Lyell (1797-1875) Uniformitarianism – geological processes & rates today are those that also operated in antiquity See timeline Fig. 22.2

  19. Western Historical Context Charles Lyell (1797-1875) Uniformitarianism – suggested that the Earth is > 6000 yr old See timeline Fig. 22.2

  20. Western Historical Context Jean Baptiste Lamarck (1744-1829) Invertebrate Curator ofthe Natural History Museum in Paris One of the 18th & 19thcenturies’ biologists who hypothesized that traits of species are not immutable, i.e., they can evolve See timeline Fig. 22.2

  21. Western Historical Context Jean Baptiste Lamarck (1744-1829) Hypothesized mechanism of evolution: Use & disuse alters traits; inheritance of acquired characters results in adaptations to environmental conditions See timeline Fig. 22.2

  22. Western Historical Context Thomas Malthus (1766-1834) English demographer Hypothesis: Plants and animals are capable of producing far more offspring than resources can support; the “struggle for existence” (e.g., famine, war) is an inescapable consequence See timeline Fig. 22.2

  23. Western Historical Context England EUROPE NORTH AMERICA ATLANTIC OCEAN PACIFIC OCEAN Galápagos Islands HMS Beagle in port AFRICA SOUTH AMERICA Darwin in 1840, after his return AUSTRALIA Cape of Good Hope Andes Tasmania Cape Horn New Zealand Tierra del Fuego Within this context, Charles Darwin(1809-1882)served as Ship’s Naturalist on the HMS Beagle’s circumnavigation of the globe (1831-1836)

  24. Galapagos Islands, Ecuador

  25. Galapagos Islands, Ecuador

  26. Galapagos Islands, Ecuador

  27. Galapagos Islands, Ecuador

  28. Darwin was a good observer of both wild and domesticated organisms (e.g., birds)

  29. Darwin was a good observer of both wild and domesticated organisms (e.g., birds)

  30. Western Historical Context Charles Darwin (1809-1882) English gentleman who conceived of natural selection as the principal mechanism of adaptive evolution See timeline Fig. 22.2

  31. Western Historical Context Alfred Russel Wallace (1823-1913) English biologist who also (independently) conceived of natural selection as the principal mechanism of adaptive evolution See timeline Fig. 22.2

  32. Western Historical Context Lyell presented the independently derived hypothesis to the Linnaean Society of London on July 1, 1858

  33. Western Historical Context Charles Darwin (1809-1882) The Origin of Species (1859)

  34. The Origin of SpeciesFinal paragraph: “It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us… There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

  35. Darwinian Theory of Evolution Descent with modification Descent implies common ancestry Modification to better suite the environment = adaptation Natural selection is the principal process that drives adaptive evolution See Fig. 22.7

  36. Darwinian Theory of Evolution Organisms have enormous potential for population increase, but the potential is rarely reached Generalized sigmoidal population growth curve

  37. Potential for rapid population growth when resources are not limiting Resource availability generally limits population size Competition for resources (“struggle for existence”) Phenotypic variability (morphology, physiology, behavior, etc.) Natural Selection: Survival and reproduction of the “fittest” individuals Some variabilityresults from heritable differences Adaptive evolution: A change in the phenotypic constitution of a population owing to selection on heritable variation among phenotypes

  38. Lamarckism Inheritance of acquired characteristics Use Darwinism Genetic inheritance from selected population Natural selection Generation 2 Generation 1

  39. Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection

  40. Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection

  41. Evidence for the Theory of Evolution by Natural Selection Darwin used artificial selection to illustrate the modifying potential of selection

  42. Evidence for the Theory of Evolution by Natural Selection Rapid changes in populations under strong selection E.g., pesticide resistance

  43. Human Cat Bat Whale Evidence for the Theory of Evolution by Natural Selection Homologous traits (a.k.a. characters, attributes) = traits in different species that arose from the same ancestral trait (may or may not have similar function) See Fig. 22.14

  44. Evidence for the Theory of Evolution by Natural Selection Even when homologies are not obvious in adults, they may be quite apparent in embryonic stages Lemur Pig Human Which one is the human?

  45. Evidence for the Theory of Evolution by Natural Selection Analogous traits = traits in different species that have similar function, but arose from different ancestral traits

  46. To distinguish homologous vs. analogous traits, the relatedness of the organisms doesn’t matter as much as the evolutionary history of the traits themselves

  47. Evidence for the Theory of Evolution by Natural Selection Analogous traits = traits in different species that have similar function, but arose from different ancestral traits

  48. Evidence for the Theory of Evolution by Natural Selection Vestigial organs = remnants of organs that had important functions in ancestors These examples happen to be homologous leg and foot bones