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DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE

DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE. CHAPTER 22. “ Nothing in Biology makes sense except in the light of evolution” T.B. Dobzhansky. Figure 22.2 Fossils of trilobites, animals that lived in the seas hundreds of millions of years ago. HISTORICAL CONTEXT.

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DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE

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  1. DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE CHAPTER 22

  2. “ Nothing in Biology makes sense except in the light of evolution” • T.B. Dobzhansky

  3. Figure 22.2 Fossils of trilobites, animals that lived in the seas hundreds of millions of years ago

  4. HISTORICAL CONTEXT • Carl Linnaeus (1707-1778) – founder of taxonomy (scientific name) grouped similar species into same genus • Georges Cuvier (1769-1832) – catastrophism – different species in layered rock due to catastrophic events like floods

  5. James Hutton (1726-1797) – gradualism – profound change is a cumulative product of slow but continuous process; ex. Rivers making canyons • Charles Lyell (1797-1875) – uniformitarianism – geological process have not changed throughout Earth’s history • Jean Baptiste Lamarck (1744-1829)- thought acquired characteristics can be passes on to offspring

  6. Figure 22.3 Formation of sedimentary rock and deposition of fossils from different time periods

  7. Figure 22.4 Strata of sedimentary rock at the Grand Canyon

  8. Figure 22.18 Charles Darwin in 1859, the year The Origin of Species was published

  9. CHARLES DARWIN (1809-1882) • Worked on the HMS Beagle in 1830’s • Observed and collected thousands of different species • Galapagos Islands (west of S. America) most interesting

  10. Figure 22.5 The Voyage of HMS Beagle

  11. Figure 22.6 Galápagos finches

  12. “The Galápagos tortoise (or Galápagos giant tortoise), is the largest living tortoise, endemic to nine islands of the Galápagos archipelago. Adults of large subspecies can weigh over 300 kilograms (660lb) and measure 1.2 meters (4 ft) long. Although the maximum life expectancy of a wild tortoise is unknown, the average life expectancy is estimated to be 150-200 years.” Source: en.wikipedia.org/wiki/Gal%C3%A1pagos_tortoise

  13. Darwin read Lyell’s Principles of Geology and felt age of earth was much older than previously thought • 1844 Darwin wrote essay on the origin of species • 1858 – Alfred Wallace sends manuscript to Darwin about Natural Selection

  14. Lyell presented Wallace’s paper as well as Darwin’s 1844 essay to scientists • 1859 The Origin of Species published by Darwin • Descent with modification • Natural selection (the mechanism)

  15. Figure 22.7 Descent with modification

  16. DARWIN’S OBSERVATIONS • Population size can lead to struggle for existence • Individuals who inherited characteristics best fit for environment are likely to have more offspring than less fit individuals • Leads to gradual change in a population

  17. NATURAL SELECTION • A population evolves, not an individual! • Acquired characteristics may be adaptable but are not inherited!! • The environment does not create a best fit characteristic, but selects for it!

  18. Figure 22.9 A few of the color variations in a population of Asian lady beetles

  19. Figure 22.11b Artificial selection: diverse vegetables derived from wild mustard

  20. Goldendoodle and a liger AP:April. 29, 2005 ST. THOMAS, Barbados - It's male.  But what is it?  A zonkey? A deebra?  That's the debate in Barbados since a zebra gave birth to a foal sired by a donkey.

  21. EVIDENCE OF EVOLUTION • Biogeography– geographical distribution of species • Ex. Islands with similar species to mainland • Fossil record – transitional forms • Comparative Anatomy – homologous structures among different organisms

  22. Vestigial organs –marginal, if any importance, remnants of structures that once served a function • Whale pelvis and leg bones and human appendix • Comparative Embryology – most vertebrates share common early development (gill slits) • Molecular Biology – similar overall DNA, similar proteins (ex. Cytochrome c)

  23. Figure 22.12 Evolution of insecticide resistance in insect populations

  24. Figure 22.13 Evolution of drug resistance in HIV

  25. Figure 22.14 Homologous structures: anatomical signs of descent with modification

  26. Table 22.1 Molecular Data and the Evolutionary Relationships of Vertebrates

  27. Figure 22.15 Different geographic regions, different mammalian “brands”

  28. Figure 22.16 The evolution of fruit fly (Drosophila) species on the Hawaiian archipelago

  29. Figure 22.17 A transitional fossil linking past and present

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