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Exploring Darwin's Theory of Evolution: From Natural Selection to Common Descent

Uncover the evolution process from ancient organisms to modern species, as observed by Charles Darwin during his voyage on the HMS Beagle. Explore concepts like natural selection, artificial selection, and evidence of evolution through fossils, body structures, and embryology. Gain insights into Lamarck's contributions, population growth impacts, and the key mechanisms driving species adaptation and survival over time.

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Exploring Darwin's Theory of Evolution: From Natural Selection to Common Descent

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  1. Chapter15 Darwin’s Theory Of Evolution

  2. 15-1 I. Evolution A. process by which modern organisms have descended from ancient organisms; change in species over time II. Charles Darwin A. Sailed around the world on HMS Beagle in 1831

  3. B. Made observations 1. Patterns of diversity: plant/animal well suited to environment 2. Living Organisms and fossils  how related (Page 370) 3. Galapagos Islands (Page 371) a. 1,000 Km W of South America b. Close together but very different climates c. Characteristics of animals/plants varied noticeably C. Hypothesis life changes over time  Now a Theory

  4. 15-2 I. Changing Earth A. Hutton and Lyell 1. Earth is many millions of years old 2. The processes that changed Earth in the past are the same processes that operate in the present B. Influence on Darwin 1. If the Earth could change over time, life might change as well.

  5. II. Species Evolve A. Lamarck’s contributions were important, even if hypothesis was incorrect. 1. Recognized a. living things have changed over time b. all species were descended from other species c. organisms were adapted to their environments 2. Proposed a. selective use or disuse of organs; organisms could acquire or lose certain traits during their life (Aka: Theory of Acquired Characteristics ) Add to notes: b. These traits could then be passed on to their offspring.

  6. A male fiddler crab uses its front claw to ward off predators and to attract mates. Page 376

  7. Because the front claw is used repeatedly, it becomes larger. This characteristic (large claw) is passed onto its offspring.

  8. 3. Hypothesis = WRONG!!! Evidence did not support his proposed hypothesis, but we still learned from it! a. We NOW know an organism’s behavior has no effect on its inherited characteristics. b. Lamarck did not know: 1.how traits are inherited 2. that an organism’s behavior has no effect on its inheritable physical (phenotypic) characteristics

  9. III. Population Growth A. 1798- Thomas Malthus noted that babies were being born faster than people were dying 1. reasoned that if the human population continued to grow = insufficient living space and food; wars, famines and disease keep these pops. “in check.” B. Darwin realized this pertains to plants and animals 1. If all offspring of any species survived for several generations = overrun the world 2. Key to Darwin’s explanation of evolutionary change

  10. 15-3 I. Darwin, 1859, published On the Origin of Species A. Proposed a mechanism for evolution called natural selection B. Evolution has been taking place for millions of years—and continues in all living things.

  11. II. Artificial Selection A. Humans select the useful characteristics provided by nature to provide the next generation Ex. Largest hogs/ fastest race horses/ largest cattle III. Natural Selection A. The Struggle for Existence 1. Organisms compete for resources (water, food, space, mates)

  12. B. Survival of the Fittest 1. Better suited to the environment = fitness 2. Adaptations = inherited characteristic that increases an organism's chance to survive Enables one species to resemble another species a. Mimicry = Milk snake Coral snake b. Camouflage = Blend into environment Leaf Frog

  13. C. The traits being selected contribute to an organism's fitness in its environment. D. Descent With Modification 1. species have descended, with changes, from other species over time All living organisms are related to one another. 2. Common Descent 

  14. IV. Evidence of Evolution • Fossil Record (Page 382) 1. compared fossils - determine that life on Earth has changed over time B.Geographic Distribution of Living Species 1. Existence of similar but unrelated species due to natural selection in similar environments

  15. 2. Similar, but unrelated species = evidence for convergent evolution = analogous structures Page 383

  16. C. Body Structures 1. Homologous Body Structures-Divergent Evolution a. Similar in arrangement/structure but may serve different functions-suggests common ancestry Page 384

  17. 2. Analogous Structures-Convergent Evolution a. NOT similar in structure but similar in function b. Two unrelated species solving the same problem example: wings on birds and butterflies 3. Vestigial Body Structures a. Reduced structure having no known modern day purpose b. Vestige = “remnant” of the past Ex: eyes on mole rats/cavefish, human appendix; human tail bone; flightless bird with wings

  18. D. Embryology 1. Embryos of vertebrates have cells that develop in the same order and in similar patterns to produce the tissues/organs 2. Tails and gill slits on all developing species

  19. Reg Ed – Summary of Theory of Evolution: 1. There is variation within the same species. 2. Organisms produce more offspring than can survive, so there is competition for resources- STRUGGLE FOR SURVIVAL 3. Individuals best adapted to the environment will survive and leave behind more offspring (their alleles) than those who are not best suited. 4. The process whereby the best suited leave behind the favorable genes is the process of NATURAL SELECTION causing change over time-EVOLUTION.

  20. Honors- Summary of Darwin's Theory 1. Individual organisms in the same species differ - some of this variation is heritable-VARIATION in a species 2. Organisms produce more offspring than can survive. 3. Because more organisms are produced than can survive, they compete for limited resources- STRUGGLE FOR existence/ survival. 4. Individuals best ADAPTED to their environment survive and reproduce most successfully(FITNESS). 5. Organisms that reproduce pass their heritable traits to their offspring. Others die or leave behind fewer offspring.

  21. 6. Natural selection causes species to change over time. 7. Species alive today are descended with modification from ancestral species that lived in the distant past. 8. This process of natural selection unites all organisms on Earth.

  22. Reg Ed – Summary of Theory of Evolution: 1. There is variation within the same species. 2. Organisms produce more offspring than can survive, so there is competition for resources- STRUGGLE FOR SURVIVAL 3. Individuals best adapted to the environment will survive and leave behind more offspring (their alleles) than those who are not best suited. 4. The process whereby the best suited leave behind the favorable genes is the process of NATURAL SELECTION causing change over time-EVOLUTION.

  23. 15-1 Darwin's observations in the Galápagos Islands included all of the following EXCEPT A. characteristics of many living organisms varied among the different Galápagos Islands. B. many plants and animals were well suited to their environments. C. very different animals inhabited many similar ecosystems. D. though close together, the islands had very different climates.

  24. 15-1 What did Darwin learn about the tortoises of the Galápagos Islands? A. Tortoises with dome-shaped shells were found on all of the islands. B. The tortoises resembled fossil remains that were found on the islands. C. The shape of the Galápagos tortoise shells varied with their different habitats. D. Different shaped tortoise shells occupied the same habitats.

  25. 15-1 According to Darwin's proposed theory of evolution, species of organisms A. change over time. B. are not related to fossil remains. C. do not vary from one location to another. D. remain unchanged when the environment changes.

  26. 15-1 Darwin hypothesized that different-looking mockingbirds from different islands might be descendants of birds that A. belonged to a single species that had originated on the islands B. belonged to a single species from the South American mainland. C. belonged to a different species from similar habitats in South America. D. had been brought to the islands by earlier visitors.

  27. 15-1 What role did the evidence gathered by Darwin play in developing his ideas? A. It immediately gave him the idea that organisms evolved. B. It confirmed evolution—an idea he had before he left England. C. It confirmed evolution, which he proved on his arrival in the Galápagos. D. It led to considering the possibility of evolution only after he was heading home.

  28. 15–2 Hutton and Lyell recognized that geological processes A. of the past differ from those of the present. B. indicate that Earth is many millions of years old. C. operate quickly, often over thousands of years. D. always involve violent events like volcanoes, earthquakes, and floods.

  29. 15–2 The discovery of many fossils challenged the idea that A. acquired traits could be inherited. B. Earth is many millions of years old. C. species had never changed over time. D. geological changes are slow.

  30. 15–2 Which of the following scientists proposed the hypothesis of selective use and disuse? A. Charles Darwin B. Jean-Baptiste Lamarck C. Thomas Malthus D. Charles Lyell

  31. 15–2 The scientist that proposed that Earth is shaped by geological forces that took place over long periods of time is: A. Malthus B. Hutton C. Darwin D. Lamarck

  32. 15–2 Darwin’s reading of Thomas Malthus made him realize that A. because of overpopulation, human beings cannot avoid extinction. B. all living things must evolve. C. living things produce more offspring than can possibly survive. D. the basic ideas of Lamarck were wrong.

  33. 15-3 The scientist who motivated Darwin to publish On the Origin of Species was A. Alfred Russel Wallace. B. Charles Lyell. C. Jean-Baptiste Lamarck. D. Thomas Malthus.

  34. 15-3 Differences among individuals of a single species are referred to as A. artificial selection. B. genetic variation. C. survival of the fittest. D. environmental adaptation.

  35. 15-3 Changes that increase a species' fitness in its environment over time are due to A. the principle of common descent. B. the geographic distribution of that species C. natural selection. D. habitat selection.

  36. 15-3 An inherited characteristic that increases an organism's chance of survival is called a(an) A. homologous structure. B. vestigial organ. C. adaptation. D. analogous structure.

  37. 15-3 Evidence used by Darwin to support the idea of evolution included all the following EXCEPT A. fossils that demonstrate change over time. B. the genetic mechanism by which useful traits are inherited. C. the geographic distribution of living things D. the presence of many homologous structures in plants and animals.

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