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  • 1. CHAPTER 13 NOTES “ THE THEORY OF EVOLUTION”
  • 2. I. THEORY OF EVOLUTION
  • 3. A. Evolution - change over a period of time
  • 4. B. Charles Darwin – English naturalist
    • 1. Studied the plants and animals of the Galapagos Islands.
    • 2. Noticed that the plants and animals of the Galapagos Islands were similar to those off the coast of South America .
  • 5. 3. Suggested that the explanation for this similarity was that their ancestors had migrated from South America to the Galapagos Islands.
  • 6. 4. Published ideas about evolution in his book “Origin of Species” – concluded that evolution occurs because of natural selection .
    • Four basic concepts:
    • Variations exist among individuals in a population
    • Variations can be inherited
    • More offspring are produced than can survive.
    • Variations that increase an organism’s chance of surviving and reproducing are more likely t be passed on to the next generation.
  • 7. II. EVOLUTION BY NATURAL SELECTION
  • 8.
    • A. Natural selection – individuals that have traits that better suit their environment are more likely to survive and reproduce successfully. “ survival of the fittest ”
    • B. Adaptation – physical and behavioral traits that allow organisms to become better suited to their environment.
        • 1. Ex: coloring of an animal to blend in to environment
        • Ex: thick leaves of a cactus to store water
        • Penguin adaptations – short wings, dense bones
    http://www.gma.org/surfing/antarctica/penguin.html
  • 9.
      • C. Gradualism – model of evolution in which change occurs at a slow , constant rate.
      • D. Punctuated Equilibrium – model of evolution in which periods of rapid change in a species are separated by periods of little or no change (possibly caused by suden or drastic changes in environment).
  • 10. III. EVIDENCE OF EVOLUTION
  • 11. A. Fossils – provide an actual record of Earth’s past life forms .
    • 1. shells, bones
    • 2. any traces of dead organisms ( leaf imprint in rock )
    • 3. footprints , insects trapped in tree sap , insects trapped in tar
  • 12. B. Anatomy and Development
    • 1. Vestigial structures – structures that have been reduced in size because they no longer serve an important function.
    • Ex: hind leg bones of whales, human appendix .
    • 2. Homologous structures – anatomical structures from a common ancestor.
    • Ex: forelimbs of vertebrates
  • 13. B. Anatomy and Development (continued)
    • 3. Embryo development – at some time in their development, all vertebrate embryos have a fin , tail , and pharyngeal pouches .
  • 14.
    • 4. Biological molecules – as species evolve, one change after another becomes part of their genetic instructions.
    • a. Closely related species will show similarities in nucleotide sequences (DNA).
    • b. Closely related species will have similar amino acid sequences (proteins)
    • c. If species have changed over time, their genes should have changed.
    B. Anatomy and Development (continued)
  • 15. IV. EXAMPLES OF EVOLUTION
  • 16. A. Darwin’s Finches
    • 1. Studied 9 distinct species
    • 2. All similar except for beak shape
    • 3. Evolved from common ancestors
    • 4. Beak shape was affected by the availability of food.
  • 17. B. Formation of New Species
    • 1. divergence – the accumulation of difference between species or populations.
    • Divergence leads to:
    • 2. speciation – process by which new species form
    • 3. subspecies – populations of the same species that differ genetically because they have adapted to different living conditions.