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What is Life?

Explore the impact of imperfect reproduction and variation on survival through animated drawings. Learn about evolutionary biology concepts like natural selection, heritable variation, and fossil records.

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What is Life?

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  1. What is Life?

  2. What will happen if organisms reproduce, imperfectly, and the variation makes a difference in survival and reproduction of the organism?

  3. School children modeled this by drawing copies of a drawing of animal. Then most of these copies were eliminated (disaster or climate change), and they drew copies of the surviving drawings, for 6 successive generations. These drawings were animated to produce this video: http://www.youtube.com/watch?v=N8X-j0dbZWs What will happen if organisms reproduce, imperfectly, and the variation makes a difference in survival and reproduction of the organism?

  4. Evolution is an inevitable consequence of life on Earth • Heritable variation – mutation, recombination. • Competition for limited resources. • Natural selection. • Time – many generations. • Long-term environmental changes.

  5. Hutton’s Unconformity Red sandstone (horizontal) Grey shale (vertical) “… no vestige of a beginning, no prospect of an end.” –James Hutton (photo: Anne Burgess) http://en.wikipedia.org/wiki/Image:Siccar_Point.jpg

  6. Homology of Mammalian Limbs • Buffon (1707-1788) noted the homologous structure of mammal limbs and suggested descent from a common ancestor. • Common structures in four very different mammals: • humerus (gray) • radius (orange) • ulna (beige) • carpals (yellow) • phalanges (brown) Campbell & Reece, Fig. 22.14

  7. Sean Carroll - http://www.hhmi.org/biointeractive/evolution/lectures.html

  8. Sean Carroll - http://www.hhmi.org/biointeractive/evolution/lectures.html

  9. What the fossil record shows Foraminiferans – www.don-lindsay-archive.org/creation/foram_work.gif

  10. Evolution of Horses

  11. Horsetoes!

  12. Darwin's Original Insights • Descent with modification from a common ancestor – a tree describes genealogy of life • Natural selection – the mechanism of evolution

  13. Darwin's Tree Illustrations 1859 Origin of Species – only figure 1837 notebook page

  14. Natural Selection and Time

  15. How often does a black coat mutation arise? Depends on:

  16. How often can we expect a black rock pocket mouse to arise by mutation? Mutation rate for black MCIR allele = 2 x 10-8

  17. Evolutionary hypotheses are testable and falsifiable • Discovery and characterization of new transitional fossils • DNA sequence comparisons • Radiometric and isotopic dating • Geological record • Astrophysics

  18. Thomas Huxley's grandchildren

  19. Modern Biology Is Evolutionary Biology • “Nothing in biology makes sense except in the light of evolution.” • Theodosius Dobzhansky • “The alternative to thinking in evolutionary terms is not to think at all.” • Peter Medawar, Nobel Laureate, 1960

  20. Useful Websites • National Academy of Sciences: Teaching About Evolution and the Nature of Science • A good overview of evolution and science. • UC Museum of Paleontology • Info on the theory and history of evolution • Talk Origins Archive • Info on evolution and creationism • Talk Origins Archive FAQ • A good entry point to the Talk Origins Archive

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