Introduction to Theory of Evolution

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Introduction to Theory of Evolution

  1. 1. Chapter 25: EvolutionBiology: Mrs. Neistadt
  2. 2. Changes Over Time: *Most species change over time. This slow, gradual change is called Evolution ____________________. Evidence shows the first living creatures were single-celled organisms living in the oceans 3 billion years ago. *Many species have become extinct. Extinct species were once living, but no longer exist.
  3. 3. Jean Baptist Lamarck In the 1800s scientists were studying and discovering __Fossils . A fossil is the remains of an organism that lived long ago. Jean Baptist Lamarck proposed one of the first theories of evolution. He thought organisms developed traits by using or not using parts of their body.  Example: Giraffes Incorrect!
  4. 4. Charles Darwin In 1831 an Englishman named Charles Darwin took a trip on the HMS Beagle. He was to map the coast of South America. He stopped on the Galapagos Islands where he began a study that would turn scientific study in a new direction. Darwin discovered the various Galapagos Islands had different species of animals. He noticed 13 species of finches. Each finch had a different beak, specialized to find food on its island.
  5. 5. Charles Darwin Charles Darwin spend 20 years thinking about his discoveries. *In 1859, Darwin wrote the book, “The Origin of Species” to explain his theories on evolution.
  6. 6. *Four Points to Darwin’s Theory: *Overproduction *Competition *Variations or Adaptations *Survival of the Fittest
  7. 7. Charles Darwin
  8. 8. Genetic Variations: Darwin did not know HOW genetic traits were passed on. *A gene pool is the combined genetic information of all members of a population. By studying the gene pool of a population, scientists can see how variations in traits are passed to offspring.
  9. 9. *Events That Can CauseEvolution: *Natural Selection *Evolution can only occur when *Mutation an event causes changes in the gene pool.*Genetic Drift
  10. 10. Natural Selection *Natural Selection is the way that organisms best suited to an environment survive
  11. 11. Mutation *Mutation: If a mutation is harmful the organism may die before passing on the gene. If the mutation is helpful, the organisms live and pass the gene on.
  12. 12. Genetic Drift Genetic Drift is changes within a gene pool that occurs due to random events, or when individuals leave or join the population.
  13. 13. 3 Types of Evolution: Divergent Convergent Coevolution Evolution Evolution Different Types of Evolution
  14. 14. Your turn…Create a graphic organizer to Compare the 3 types of evolution: Divergent Convergent Coevolution Use Internet research and/or your textbook Pg398 to help you.

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