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Evolution                    by             Natural SelectionAP Biology                       2006-2007
DOCTRINEAP Biology           TINTORETTO   The Creation of the Animals 1550
But the Fossil record…             OBSERVATIONAP Biology
mya Quaternary                                                                                                           M...
LaMarck    Organisms adapted to      their environments by      acquiring traits            change in their life time   ...
Charles Darwin    1809-1882    British naturalist    Proposed the idea      of evolution by      natural selection    ...
Voyage of the HMS Beagle    Invited to travel around the world        1831-1836 (22 years old!)        makes many obser...
Voyage of the HMS Beagle     Stopped in Galapagos Islands            500 miles off coast of EcuadorAP Biology
Succession of types    Armadillos are native to the    Americas, with most species    found in South America.             ...
Mylodon (left) Giant                                        ground sloth (extinct)             Modern sloth (right)       ...
Unique speciesAP Biology
Darwin found… birds     Collected many     different birds on the     Galapagos Islands.                           Finch? ...
But Darwin found… a lot of finchesDarwin was amazed tofind out:All 14 species of birdswere finches…But there is only onesp...
Tree ThinkingDescendant species   Ancestral       Large-seed eater?                     Large Ground      Small-seed eater...
Correlation of species to food source     Seed        Flower            Insect    eaters       eaters            eaters   ...
Darwin’s finches    Differences in beaks          associated with eating different foods          survival & reproducti...
Darwin’s finches   Darwin’s conclusions          small populations of original South American           finches landed o...
Seeing this gradation &                        diversity of structure in             one small, intimately related group o...
Darwin’s finches     Differences in       beaks allowed       some finches to…         successfully          compete    ...
More observations…   Correlation of species                             to food source                          Whoa,     ...
Many islands also show                  distinct local variations in                  tortoise morphology…              …p...
Artificial selectionThis is not just aprocess of thepast…                                        It is all                ...
Selective   breeding   the raw genetic   material (variation)   is hidden thereAP Biology
Selective breeding      Hidden variation      can be exposed      through selection!AP Biology
In historical context      Other people’s ideas paved the       path for Darwin’s thinking                               ...
A Reluctant Revolutionary    Returned to England in 1836          wrote papers describing his collections           & ob...
And then came the letter….   Then, in 1858, Darwin received a letter   that changed everything…      Alfred Russel Wallace...
The time was ripe for the idea!                     To Lyell—                         Your words                      have...
Voyage: 1831-1836    November 24, 1859, Darwin published“On the Origin of Species by Means of Natural Selection” AP Biology
Essence of Darwin’s ideas    Natural selection        variation exists in populations        over-production of offspri...
LaMarckian vs. Darwinian view    LaMarck            in reaching higher             vegetation giraffes             stret...
Stick your neck out…           Ask Questions!AP Biology
Ghosts of Lectures Past                    (storage)AP Biology                             2009-2010
Life has changed over time       & in turn has changed the Earth                              Living creatures have       ...
Evolution as Change Over Time                        idea accepted             Evolution!                        before Da...
Galapagos    Recent volcanic origin most    of animal species on the    Galápagos live nowhere else    in world, but they ...
Coherent explanation of observations                "Nothing in biology                makes sense except in              ...
Essence of Darwin’s ideas              (1) Variation exists in natural populations              (2) Many more offspring ar...
Stick your neck out…                Ask Questions!AP Biology
The Birds…     Galápagos birds            22 of the 29 species of             birds on the Galapagos             are end...
Darwin’s finches    Darwin was amazed      to find out they were      all finches            14 species            but ...
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02 ch22evolutiondarwin2009

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02 ch22evolutiondarwin2009

  1. 1. Evolution by Natural SelectionAP Biology 2006-2007
  2. 2. DOCTRINEAP Biology TINTORETTO The Creation of the Animals 1550
  3. 3. But the Fossil record… OBSERVATIONAP Biology
  4. 4. mya Quaternary Molluscs Anaerobic Bacteria Jawless Fish Teleost Fish Multicellular Animals Chordates Land Plants Photosynthetic Bacteria Green Algae Seed Plants Arthropods Amphibians Mammals Birds Flowering Plants Insects Reptiles 1.5 Tertiary 63 Cretaceous Dinosaurs 135 Jurassic 180 Triassic 225 Permian 280 Carboniferous 350 Devonian 400 Silurian 430 Ordovician 500 Cambrian 570 Ediacaran 700 Precambrian, Proterozoic, & Archarozoic 4500Life’s Natural History is a record of Successions & Extinctions AP Biology
  5. 5. LaMarck  Organisms adapted to their environments by acquiring traits  change in their life time  Disuse organisms lost parts because they did not use them — like the missing eyes & digestive system of the tapeworm  Perfection with Use & Need the constant use of an organ leads that organ to increase in size — like the muscles of a blacksmith or the large ears of a night-flying bat  transmit acquired characteristics to next generationAP Biology
  6. 6. Charles Darwin  1809-1882  British naturalist  Proposed the idea of evolution by natural selection  Collected clear evidence to support his ideasAP Biology
  7. 7. Voyage of the HMS Beagle  Invited to travel around the world  1831-1836 (22 years old!)  makes many observations of nature  main mission of the Beagle was to chart South American coastline Robert FitzroyAP Biology
  8. 8. Voyage of the HMS Beagle  Stopped in Galapagos Islands  500 miles off coast of EcuadorAP Biology
  9. 9. Succession of types Armadillos are native to the Americas, with most species found in South America. Why should extinct armadillo-like species & living armadillos be found on the same continent?Glyptodont fossils are alsounique to South America. AP Biology
  10. 10. Mylodon (left) Giant ground sloth (extinct) Modern sloth (right) “This wonderful relationship in the same continent between the dead and the living will…throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts.”AP Biology
  11. 11. Unique speciesAP Biology
  12. 12. Darwin found… birds Collected many different birds on the Galapagos Islands. Finch? Sparrow? Thought he found very different kinds…AP Biology Woodpecker? Warbler?
  13. 13. But Darwin found… a lot of finchesDarwin was amazed tofind out:All 14 species of birdswere finches…But there is only onespecies of finch on the LargeFinch? Ground Finch? Sparrow? Small Ground Sparrow?mainland! Finch Finch How did one species of finches become so many different species now?AP Biology Woodpecker? Warbler Finch Woodpecker? Warbler? Veg. Tree Finch Warbler?
  14. 14. Tree ThinkingDescendant species Ancestral Large-seed eater? Large Ground Small-seed eater? Small Ground species Finch FinchAP Biology Warbler? Warbler Finch Leaf-browser? Veg. Tree Finch
  15. 15. Correlation of species to food source Seed Flower Insect eaters eaters eaters Rapid speciation: new species filling new niches, because they inherited successful adaptations.Adaptive radiation AP Biology
  16. 16. Darwin’s finches  Differences in beaks  associated with eating different foods  survival & reproduction of beneficial adaptations to foods available on islands Warbler finch Cactus finch Woodpecker finch Sharp-beaked finch Small insectivorous er Small ground tree finch Warbl finch finch Gr es Large Cactus ou ch insectivorous Medium nd fin eater tree finch ground finch fin ee Insect eaters Tr ch Seed eaters es Vegetarian Bud eater Large tree finchAP Biology ground finch
  17. 17. Darwin’s finches  Darwin’s conclusions  small populations of original South American finches landed on islands  variation in beaks enabled individuals to gather food successfully in the different environments  over many generations, the populations of finches changed anatomically & behaviorally  accumulation of advantageous traits in population  emergence of different speciesAP Biology
  18. 18. Seeing this gradation & diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species has been taken & modified for different ends.AP Biology
  19. 19. Darwin’s finches  Differences in beaks allowed some finches to…  successfully compete  successfully feed  successfully reproduce  pass successful traits onto their offspringAP Biology
  20. 20. More observations… Correlation of species to food source Whoa, Turtles, too! AP Biology
  21. 21. Many islands also show distinct local variations in tortoise morphology… …perhaps these are the first steps in the splitting of one species into several?AP Biology
  22. 22. Artificial selectionThis is not just aprocess of thepast… It is all aroundAP Biology us today
  23. 23. Selective breeding the raw genetic material (variation) is hidden thereAP Biology
  24. 24. Selective breeding Hidden variation can be exposed through selection!AP Biology
  25. 25. In historical context  Other people’s ideas paved the path for Darwin’s thinking competition: struggle for survival population growth exceeds food supply land masses change over immeasurable timeAP Biology
  26. 26. A Reluctant Revolutionary  Returned to England in 1836  wrote papers describing his collections & observations  long treatise on barnacles  draft of his theory of species formation in 1844  instructed his wife to publish this essay upon his death  reluctant to publish but didn’t want ideas to dieAP Biology with him
  27. 27. And then came the letter…. Then, in 1858, Darwin received a letter that changed everything… Alfred Russel Wallace a young naturalist working in the East Indies, had written a short paper with a new idea. He asked Darwin to evaluate his ideas and pass it along for publication.AP Biology
  28. 28. The time was ripe for the idea! To Lyell— Your words have come true with a vengeance… I never saw a more striking coincidence…so all my originality, whatever it may amount to, will be smashed.AP Biology
  29. 29. Voyage: 1831-1836 November 24, 1859, Darwin published“On the Origin of Species by Means of Natural Selection” AP Biology
  30. 30. Essence of Darwin’s ideas  Natural selection  variation exists in populations  over-production of offspring  more offspring than the environment can support  competition  for food, mates, nesting sites, escape predators  differential survival  successful traits = adaptations  differential reproduction  adaptations become moreAP Biology common in population
  31. 31. LaMarckian vs. Darwinian view  LaMarck  in reaching higher vegetation giraffes stretch their necks & transmits the acquired longer neck to offspring  Darwin   giraffes born with longer necks survive better & leave more offspring who inherit their long necksAP Biology
  32. 32. Stick your neck out… Ask Questions!AP Biology
  33. 33. Ghosts of Lectures Past (storage)AP Biology 2009-2010
  34. 34. Life has changed over time & in turn has changed the Earth Living creatures have changed Earth’s environment, making other life possibleAP Biology
  35. 35. Evolution as Change Over Time idea accepted Evolution! before Darwin Evolution! Evolution! Evolution!AP Biology
  36. 36. Galapagos Recent volcanic origin most of animal species on the Galápagos live nowhere else in world, but they resemble species living on South American mainland.AP Biology 500 miles west of mainland
  37. 37. Coherent explanation of observations "Nothing in biology makes sense except in the light of evolution." -- Theodosius Dobzhansky March 1973 Geneticist, Columbia University (1900-1975)AP Biology 2006-2007
  38. 38. Essence of Darwin’s ideas (1) Variation exists in natural populations (2) Many more offspring are born each season than can possibly survive to maturity (3) As a result, there is a struggle for existence - competition (4) Characteristics beneficial in the struggle for existence will tend to become more common in the population, changing the average characteristics of the population - adaptations(5) Over long periods of time, and given a steady input of new variation into a population, these processes lead toAP Biologyemergence of new species the
  39. 39. Stick your neck out… Ask Questions!AP Biology
  40. 40. The Birds…  Galápagos birds  22 of the 29 species of birds on the Galapagos are endemic  found only on these islands  collected specimens of all  One particular group…  at first, he paid little attention to a series of small birds  some were woodpecker- like, some warbler-like, & some finch-likeAP Biology
  41. 41. Darwin’s finches  Darwin was amazed to find out they were all finches  14 species  but only one species on SouthLarge-seed eater? Finch? Small-seed eater? Sparrow? American mainland  500 miles away  all the birds had to originally come How did from mainland one species of finches become species so many different ones now?AP Biology Warbler? Warbler? Leaf-browser? Wren?

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