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Evolution by Natural Selection

Evolution by Natural Selection. No Genetic Change Through Time (no evolution). Scientists believed that all organisms were exactly how they have always been. Then Lamarck came to town. Jean Baptiste Lamarck French biologist Explained evolution! Wrong  Acquired Traits.

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Evolution by Natural Selection

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  1. Evolution byNatural Selection

  2. No Genetic Change Through Time (no evolution) Scientists believed that all organisms were exactly how they have always been.

  3. Then Lamarck came to town • Jean Baptiste Lamarck • French biologist • Explained evolution! • Wrong  • Acquired Traits. • Artistic ability, Math ability, etc.

  4. Darwin’s Life • Charles Darwin • Wanted to be a doctor • Couldn’t stand the sight of blood • Married his cousin • Sea voyages • Voyage of Beagle • Naturalist

  5. On the HMS Beagle • 5 year journey • Observed flora/fauna everywhere he went • Catalogued • Compared • Developed his theory based on observations and evidence. • Wrote several books • Most famous was “On the Origin of Species”

  6. P.S. Mr. Chaney’s Favorite Book by Darwin is . . . • Drum roll please . . . • “The Formation of Vegetable Mould Through the Action of Worms.”

  7. Darwin’s Theory • “Descent with Modification.” • All species arise from pre-existing species • Generations pass, and species may change if the population has: • Genetic Variation • An Overproduction of offspring • A Struggle to Survive • Differential Reproduction • *********Darwinian Fitness ********* So no one else figured this out until Darwin?!?!

  8. Who has greater “Darwinian Fitness?”

  9. Evidence for Evolution: Fossils • Fossil Record • Rocks form in layers • Organisms in deeper, “older” rock, are older • Different organisms lived at different times • Today’s organisms are different from those of the past

  10. Pennyslvania’s State Fossil! • The Trilobite

  11. Example of Fossil that supports evolution Megatherium

  12. Big Birds

  13. Transition • Fossils in adjacent layers are more alike than fossils from far apart layers

  14. Evidence of Evolution: Transitional Species • Fossils of “in-between” organisms • Used as a timeline! • Speaking of trilobites . . . . Here’s a Pakicetus! (not a good transition!) Pakicetus

  15. Vestigial Traits Vestige- a mark, trace, or sign

  16. Archaeopteryx Bird? Or Reptile?

  17. Vestigial Traits Snake “spurs” Vestigial Wings in Drosophila Diptera-Vestigial Wings

  18. Xanthopanmorganiipraedicta • “Predicted Moth” • Darwin predicted it’s existence before it had been observed. • Ridiculed by other scientists • Orchids have specific pollinators

  19. Let’s Process! • 1. How does the presence of vestigial traits support the theory of evolution by natural selection? • 2. Why is variation necessary for natural selection to occur • 3. If a natural disaster wiped out all the small seeds in an area with a population of birds with varying beak size, how might the population be affected?

  20. Darwinian Fitness Who has GREATER fitness from the perspective of Darwin, and the theory of natural selection?

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