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Chapter 1 Summary

Key Takeaways

  •  Evolution Is a Scientific Theory Explaining Life’s Diversity: Evolution is the well-supported scientific theory that explains how populations change over generations through inherited traits. It accounts for the origin, diversity, and interconnectedness of all life forms via common ancestry—not as speculation, but as evidence-based science supported by genetics, fossils, anatomy, and molecular biology.
  • Fossil Discoveries Challenged the Idea of Static Species: The belief that species were fixed was overturned by fossil evidence of extinct organisms like mastodons, ammonites, and ichthyosaurs. These findings led early naturalists to conclude that species could indeed change or disappear, laying the groundwork for theories of evolution.
  • Darwin’s Observations on the HMS Beagle Led to Natural Selection: During his voyage, Darwin observed how species like finches, tortoises, and marine iguanas had adapted to different environments. These insights, influenced by geological and economic theories, led him to propose natural selection—the process by which advantageous traits become more common over generations.
  • Multiple Lines of Evidence Support Evolution and come from:
    • Fossils showing gradual changes in species over time
    • Comparative anatomy revealing homologous and vestigial structures;
    • Biogeography demonstrating species distributions explained by plate tectonics;
    • Embryonic development shows similar stages among related species;
    • Genetic similarities across all life, confirming common ancestry.
  • Evolution Proceeds Through Multiple Mechanisms: Besides natural selection, evolution is driven by:
    • Mutations (random genetic changes),
    • Genetic drift (random changes in small populations),
    • Gene flow (migration of individuals/genes between populations),
      These processes contribute to genetic variation, which is essential for evolution.
  • Natural Selection Shapes Populations in Diverse Ways and can result in: :
    • Stabilizing selection (favoring average traits),
    • Directional selection (shifting traits in one direction),
    • Disruptive selection (favoring extremes),
    • Frequency-dependent selection (favoring traits based on how common they are),
    • Sexual selection (favoring traits that improve mating success).
      These patterns explain how species adapt to changing environments and ecological niches over time.

OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Summarize the following content into six key takeaways.

Flashcards

Click on the flashcards to review key terms discussed in this chapter.

 

Text Description
Front of Card:
  1. Dialog Text: Fossils
  2. Dialog Text: Charles Lyell
  3. Dialog Text: Diversifying or disruptive selection
  4. Dialog Text: Marsupials
  5. Dialog Text: Ichthyosaurus
  6. Dialog Text: Types of structures examined in comparative anatomy
  7. Dialog Text: Vestigial structures
  8. Dialog Text: Sexual dimorphism
  9. Dialog Text: Founder effect
  10. Dialog Text: Sexual selection
  11. Dialog Text: Alfred Russel Wallace
  12. Dialog Text: Continental drift
  13. Dialog Text: Analogous structures
  14. Dialog Text: Frequency-dependent selection
  15. Dialog Text: Giant tortoises
  16. Dialog Text: Piloerection
  17. Dialog Text: Genetic drift
  18. Dialog Text: Homologous structures
  19. Dialog Text: Charles Darwin
  20. Dialog Text: Tetrapods
  21. Dialog Text: Evidence of evolution
  22. Dialog Text: Evolution
  23. Dialog Text: Outcomes of natural selection
  24. Dialog Text: Overproduction
  25. Dialog Text: Mastodon
  26. Dialog Text: Stabilizing selection
  27. Dialog Text: Natural selection
  28. Dialog Text: HMS Beagle
  29. Dialog Text: Adaptation
  30. Dialog Text: Requirements of natural selection
  31. Dialog Text: Types of genetic drift
  32. Dialog Text: Heritability
  33. Dialog Text: Marine iguanas
  34. Dialog Text: Mutation
  35. Dialog Text: Variation
  36. Dialog Text: Thomas Malthus
  37. Dialog Text: Jean-Baptiste Lamarck
  38. Dialog Text: Finches
  39. Dialog Text: Ammonites
  40. Dialog Text: Galápagos Islands
  41. Dialog Text: Directional selection
  42. Dialog Text: Biogeography
  43. Dialog Text: Mechanisms of evolution
  44. Dialog Text: Gene flow
  45. Dialog Text: Bottleneck effect
  46. Dialog Text: Selective pressures
  47. Dialog Text: Genetic variation
Back of Card:
  1. Preserved remains or traces of ancient organisms; provide evidence for evolution
  2. Geologist who argued that Earth changes slowly over time; influenced Darwin’s thinking
  3. Natural selection that favors both extremes of a trait; intermediate phenotypes are often less fit
  4. Mammals with pouches; their distribution supports ideas of continental drift and evolution
  5. An extinct marine reptile; its fossil helped prove that extinction is real
  6. Homologous structures, analogous structures, vestigial structures
  7. Body parts that have lost their original function through evolution
  8. Differences in appearance between males and females of the same species, often due to sexual selection
  9. Genetic drift that occurs after a small number of individuals colonize a new area, leading to different allele frequencies
  10. Type of natural selection that occurs when individuals with certain traits are more likely to attract mates and reproduce
  11. Independently developed a theory of natural selection similar to Darwin’s
  12. The movement of Earth’s continents; explains patterns in fossil and species distribution
  13. Body parts with similar function but different structure; result from convergent evolution
  14. Type of natural selection that favors phenotypes that are either common or rare
  15. Galápagos animals with varied shell shapes and beak lengths; helped Darwin see adaptation to environment
  16. Hair standing up (e.g., goosebumps); a vestigial response in humans
  17. A mechanism of evolution due to random changes in allele frequencies, especially in small populations
  18. Body parts with similar structure but different functions; show common ancestry
  19. Developed the theory of evolution by natural selection
  20. Four-limbed vertebrates; their forelimbs are homologous structures
  21. 1) Fossils, 2) Comparative Anatomy, 3) Biogeography, 4) Embryonic Development, 5) Genetic Evidence
  22. The change in the genetic makeup of populations over generations, often resulting in new species
  23. Stabilizing Selection, Directional Selection, Disruptive Selection
  24. More offspring are produced than can survive, leading to competition
  25. An extinct relative of elephants; fossil evidence helped support the idea of extinction and change over time
  26. Natural selection that favors an average phenotype, selecting against extreme variation
  27. The process by which individuals with favorable traits are more likely to survive and reproduce
  28. The ship on which Darwin traveled and made observations that led to his theory of evolution
  29. A heritable trait that improves an organism’s ability to survive and reproduce in its environment
  30. Variation, Heritability, Differential Reproductive Success
  31. Bottleneck effect, Founder effect
  32. The ability of a trait to be passed from one generation to the next
  33. Galápagos reptiles that swim and feed in the ocean; helped Darwin see adaptation to environment
  34. A change in DNA; the source of new genetic variation
  35. Differences among individuals in a population; essential for natural selection
  36. Economist who proposed that populations grow faster than resources; influenced Darwin
  37. Proposed an early theory of evolution involving inheritance of acquired traits
  38. Birds from the Galápagos Islands; differences in their beaks helped Darwin develop his theory of natural selection
  39. Extinct marine mollusks with spiral shells; their fossils suggested that species can go extinct
  40. Location where Darwin observed unique species that influenced his ideas on evolution
  41. Natural selection that selects for phenotypes at one end of the spectrum of existing variation
  42. The study of where organisms live; supports evolution through geographic distribution
  43. Mutations, Genetic Drift, Gene Flow, Natural Selection
  44. Movement of genes between populations; can introduce new traits
  45. Genetic drift that occurs when a chance event causes a sharp reduction in population size, reducing genetic diversity
  46. Environmental factors that influence which individuals in a population survive and reproduce; e.g. predators, climate, food availability, or competition
  47. The differences in DNA sequences among individuals in a population which leads to differences in traits; Provides the raw material for natural selection to act upon

OpenAI. (2025). ChatGPT. [Large language model]. https://chat.openai.com/chat
Prompt: Provide definitions for all the bolded terms in the shared content and list all the terms in alphabetical order.

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