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17.1 History of Evolutionary Thought
  • Evolution has two aspects: descent from a common ancestor and adaptation to the environment.
  • In the eighteenth century, scientists became especially interested in classifying and understanding the relationship among all the many forms of present and past life.
  • Gradually, in the eighteenth century, scientists began to gather evidence and accept the idea that life forms do change over time. Explanations for change varied.
  1. What did Darwin mean by the statement "descent with modification"?
  2. What is the inheritance of acquired characteristics and why has this hypothesis been rejected?
Essential Study Partner Summaries of major points:
  1. Darwin's voyage
  2. Mid-eighteenth century contributions
  3. Late eighteenth century contributions
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17.2 Darwin's Theory of Evolution
  • Charles Darwin's trip around the southern hemisphere aboard the HMS Beagle provided him with evidence that the earth is very old and that evolution does occur.
  • Both Darwin and Alfred Wallace proposed natural selection as a mechanism by which adaptation to the environment takes place. This mechanism is consistent with our present-day knowledge of genetics.
  1. What affect did the geologic age of the earth (as proposed in Charles Lyell's book) have on Darwin's thinking?
  2. What is biogeography?
  3. Describe natural selection.
  4. True or False: Natural selection results in a population perfectly adapted to its environment.
  5. Natural selection acts on the ____________ (phenotype or genotype) of an individual, but alters the _______________ (phenotype or genotype) of the population.
  6. Define fitness and explain what it means to be relative.
Essential Study Partner Summaries of major points:
  1. Darwin's background
  2. Geology and fossils
  3. Biogeography
  4. Natural selection and adaptation
  5. Organisms have variations
  6. Organisms struggle to exist
  7. Organisms differ in fitness
  8. Organisms become adapted
  9. 'On Origin of Species' by Darwin
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17.3 Evidence for Evolution
  • The fossil record, biogeography, comparative anatomy, and comparative biochemistry support a hypothesis of common descent.
  1. How does the fossil record support the theory of evolution?
  2. What is the difference between homologous and analogous structures?
Essential Study Partner Summaries of major points:
  1. Common descent adapted
  2. Fossil evidence
  3. Biogeographical evidence
  4. Anatomical evidence
  5. Biochemical evidence
  6. Because it is supported by so many lines of evidence, evolution is no longer considered a hypothesis
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