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Evolution by Natural Selection: Charles Darwin's Observations

Explore how Charles Darwin's observations of different species like tortoises and finches led to his Theory of Natural Selection, shaping our understanding of evolution and the adaptation of species over time.

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Evolution by Natural Selection: Charles Darwin's Observations

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  1. Chapter 3, Lesson 3 How Do New Species Evolve?

  2. Charles Darwin • Naturalist- studies nature • His job was to collect and describe as many different species as possible • 1835- His belief was that a species didn’t change.

  3. Charles Darwin • He sailed the HMS Beagle 1831-1835 • In 1835 he reached the Galapagos Islands • Stayed about 5 weeks visiting some of the islands • Islands were in natural state– few people

  4. Charles Darwin

  5. Charles Darwin • There he made many observations by studying: *topography *landscapes * specimens of plants, animals • His observations changed his view on species

  6. Tortoises • Darwin was able to tell where a species came from based on its appearance -Islands with a lot of vegetation and grass *Structural adaptation - larger - rounded, dome shell - short legs/necks

  7. Tortoises • Islands with little vegetation and grass *Structural adaptation - smaller - longer legs - smaller shell with curved up front edge

  8. Can you tell which tortoise is which?

  9. Finches • Observed 13 different species of finches • Different beaks based on the food they ate - long or short beaks

  10. Finches

  11. Natural Selection • Darwin spent the next 20 years studying his observations • He came up with the Theory of Natural Selection *The idea that organisms that best adapted to their environment will be the ones most likely to survive and reproduce.

  12. Natural Selection • 4 main points to Darwin’s theory 1) Organisms usually produce more offspring than can survive. Example: frog eggs

  13. Natural Selection 2) Competition often exists between male mammals to win a mate. The winner will reproduce and pass on their traits. Example: Antelopes fight for a mate.

  14. Natural Selection 3) Organisms best adapted to their environment are the ones most likely to survive. If they survive they are able to reproduce and pass on traits. Example: Peppered Gray moths

  15. Natural Selection 4) Parents pass on their traits. Offspring often looks like parents but variations may occur. Example: Shell variations

  16. Structural Adaptations • Any body parts or coloring that helps an organism survive. • Examples: Cactus, Mole Rat, Peppered Moths

  17. Structural Adaptations • Cactus: Spines= protection Waxy skin= retains water, little evaporation

  18. Structural Adaptations • Mole Rat Larger teeth/claws= tunnel underground Whiskers= feel with them

  19. Structural Adaptations • Peppered Moths -In cities where factories left soot on trees, the moths became darker to blend in.

  20. New Species Over Time • Population- All the members of one species that live in a certain place.

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