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Darwin’s Case

Darwin’s Case. Chapter 15-3. The Origin of Species. In 1836, Darwin returned to England with specimens and data from all over the world and a new theory. He wanted to present his work to the scientific community, but was afraid of rejection.

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Darwin’s Case

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  1. Darwin’s Case Chapter 15-3

  2. The Origin of Species • In 1836, Darwin returned to England with specimens and data from all over the world and a new theory. • He wanted to present his work to the scientific community, but was afraid of rejection. • In 1858, a fellow naturalist, Alfred Russel Wallace, published an essay presenting evolution. • Darwin used this to motivate him to finally publish The Origin of Species which outlined his theory of evolution.

  3. Natural Selection • Inherited Variation: Darwin noticed that there are variations within species. • For example, some plants gave bigger fruit or some cows made more milk • Struggle for Existence: With limited resources, organisms will be forced into a competition for resources • Fitness: the ability to survive and reproduce. • Adaptation: any inherited characteristic that increases an organism’s chance of survival.

  4. What is this organism’s adaptation?

  5. What is this organism’s adaptation?

  6. What is this organism’s adaptation?

  7. What is this organism’s adaptation?

  8. Natural Selection • Survival of the Fittest: Individuals that are best suited to their environment (with adaptations that enable fitness) will survive and reproduce. • Darwin also called this natural selection • Because of natural selection, living species has descended, with changes, from other species over time (descent with modification) • Some examples…

  9. Natural Selection • To prove my point, here’s an example: • Humans, just like every other organism, undergo natural selection. • Humans have variation! Humans have different traits! • What traits, or variations do humans have that would make them survive and reproduce?

  10. Who would you pick?

  11. Who would you pick?

  12. Natural Selection • So what would happen to the two gentlemen? • The first guy would reproduce and his offspring (children) would look like him • The second guy would not reproduce and would not have any offspring • Let’s go back to the giraffe…

  13. Millions of years ago, some individuals of a species had longer necks than others… • Those animals with longer necks were able to eat fruit on trees while the shorter necks died off. • The animals with longer necks reproduced, and their offspring had even longer necks. • This process repeated until you have animals with extremely long necks  giraffes!

  14. Eventually, these giraffes took over the toy industry…

  15. Now You Try… • Pick an animal • Pick a trait on that animal • Explain, using pictures and captions, how this animal acquired this particular trait. • Divide a paper by 8 and use 4-8 boxes to explain your animal.

  16. Evidence of Evolution • Fossil Record: Fossils show that earth is millions of years old and species change over time • Geographic Distribution of Living Species: Different animals evolve similar characteristics due to the environment

  17. Beaver Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara NORTH AMERICA Muskrat Capybara SOUTH AMERICA Coypu

  18. Turtle Alligator Bird Mammal Ancient lobe-finned fish Evidence of Evolution • Homologous Body Structures: Structures that come from the same embryonic tissue, but end up with different mature forms.

  19. Evidence of Evolution • Similarities in Embryology: The early stages of many animals are very similar. • Let’s play a game… • Embryos shown are that of a human, fish, salamander, pig, chicken, and tortoise. Which one is which?

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