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Darwin’s Theory of Evolution

Darwin’s Theory of Evolution. Chapter 15. Charles Darwin: born in England; lived from 1809-1882. Charles Darwin. son of a doctor, Dr Robert Darwin grandfather, Erasmus, was also a doctor Darwin went to medical school to become a doctor Never became a doctor; studied theology

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Darwin’s Theory of Evolution

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  1. Darwin’s Theory of Evolution • Chapter 15

  2. Charles Darwin: born in England; lived from 1809-1882

  3. Charles Darwin • son of a doctor, Dr Robert Darwin • grandfather, Erasmus, was also a doctor • Darwin went to medical school to become a doctor • Never became a doctor; studied theology • Decided to become a clergyman

  4. His voyage… • Invited to join a voyage by friend • Friend recommended Darwin as the naturalist for the voyage • primary mission was to map the coast of South America • Intended two years on the HMS Beagle--> lasted ~5

  5. H.M.S. Beagle (1831)

  6. Galapagos Islands and South America

  7. Chapter 15 Worksheet • You may work with a partner • Get a textbook- turn to page 370

  8. Influences on Darwin • Lyell • Hutton • Malthus • Lamarck

  9. James Hutton and Charles Lyell Geologists from the 1700’s and 1800s

  10. Thomas Malthus (late-eighteenth century economist) Population will grow faster than the space and food can support

  11. Jean-Baptiste Lamarck • In 1809, the year Darwin was born, Lamarck published his idea of how organisms changed over time.

  12. Lamarck • 1st scientist to recognize that living things have changed over time: • species were descended from other species • Organisms were somehow adapted to their environment

  13. Lamarck’s proposal: Lamarckism or Lamarckian inheritance • By selective use or disuse of organs, organisms acquire or lost certain traits during their lifetime. • These traits could be passed on to their offspring. • Over time, this process led to change in a species. Now, Sticky’s offspring will have muscles! Right?! Sticky Sticky started weight lifting

  14. Lamarck’s idea in picture form Lamarck’s idea- Happens in one lifetime*

  15. Acquired characteristics • Main idea from Lamarck: • Acquired characteristics: changes in the structure or function of an organism that are the result of use, disuse, environmental influences, disease, mutilation, etc. • Inheritance of acquired characteristics states that any transformation in the parent will be inherited by the offspring.

  16. Lamarck vs Darwin IMPORTANT! This may NOT be why giraffe’s have long necks! This is strictly an example.

  17. Lamarck vs. Darwin: EXIT CARD • Think about Lamarck and Darwin’s evolutionary ideas: • Which makes more sense and why? • How would you argue against the one the makes the least sense?

  18. Darwin Published: On the Origin of Species by Means of Natural Selection, (1859) or “The Origin of Species” • Darwin’s ideas: • 1) evolution did occur • 2) evolutionary change was gradual, requiring thousands to millions of years; • 3)primary mechanism for evolution was a process called natural selection • 4)millions of species alive today arose from a single original life form through a branching process called “speciation”

  19. Darwin’s findings • Did not publish his book for 20 twenty years • Why? • Alfred Russel Wallace, another naturalist, developed similar ideas • Darwin’s publication began the development to what is now called the theory of evolution

  20. Natural Selection • process by which traits become more or less common in a population due to survival or reproduction of their organism • Variation within a population allows for selection to occur

  21. Natural Selection observed by Darwin- “Darwin’s Finches”

  22. Example of natural selection: Who would survive? Which bird would be successful at cracking open this seed with its beak? Why? What would happen to the other bird?

  23. Natural Genetic variation: • If you take a large enough sample size, you could measure any one trait from any population (one species) and find that the measurements create a bell curve • I did just that with my students!

  24. Let’s pretend… • There is only one jar with food available. • You are not allowed to share the food with anyone who cannot get it themselves.(and no, you can’t tip it over) • The jar opening is 20 cm wide. • Who will survive? • What will happen if we make another graph a few generations from now?

  25. Directional selection Original population variation New population variation after selection

  26. Stabilizing selection • The environment of the mouse changed and the only place to live was brown hay. • Which color mouse would have the easiest time hiding in the brown hay? • If it hid well, then it would survive and hopefully reproduce. • What would the graph look like generations from now?

  27. Disruptive selection • The environment the butterflies live in has changed. • Now, there are only white or purple flowers. • Which butterflies will have the hardest time hiding? • If it cannot hide well, will predators (things that eat it) be more successful? • Which butterflies will hide well, survive more often and reproduce? • How will the graph look a few generations from now?

  28. Patterns of natural selection

  29. Explain the difference… • What is the difference between natural selection, selective breeding (aka artificial selection) and inbreeding. • How does each type of selection and breeding affect the genetics of the population?

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