Evolution natural selection

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  • Evolution natural selection

    1. 1. Natural Selection 10th May 2010
    2. 2. Learning Outcome • I can explain why there are so many different species of animals and plants • I can describe how these species have changed over time
    3. 3. Lamarck
    4. 4. Lamarckian Evolution
    5. 5. Lamarckian Evolution
    6. 6. Lamarckian Evolution • Animals and plants notice that the environment has changed
    7. 7. Lamarckian Evolution • Animals and plants notice that the environment has changed • Animals and plants choose to change to better fit the environment
    8. 8. Lamarckian Evolution • Animals and plants notice that the environment has changed • Animals and plants choose to change to better fit the environment • WARNING
    9. 9. Lamarckian Evolution • Animals and plants notice that the environment has changed • Animals and plants choose to change to better fit the environment • WARNING • There is no evidence for this or explanation of how this works
    10. 10. Darwin
    11. 11. Darwin • If all offspring reproduced, the population would grow
    12. 12. Darwin • If all offspring reproduced, the population would grow • Populations stay almost constant
    13. 13. Darwin • If all offspring reproduced, the population would grow • Populations stay almost constant • Resources such as food, space and breeding partners are limited
    14. 14. • There is a struggle for survival
    15. 15. • Individuals in a population vary significantly from one another
    16. 16. • Individuals in a population vary significantly from one another • Most of this variation is inherited
    17. 17. • Individuals less suited to the environment are less likely to survive and less likely to reproduce;
    18. 18. • Individuals less suited to the environment are less likely to survive and less likely to reproduce; • Individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their inheritable traits to future generations
    19. 19. • This slow process results in populations changing to adapt to their environments, and these variations add up over time to form new species
    20. 20. Fossil Evidence
    21. 21. Fossil Evidence • Fossils are when a dead animal or plant is buried in mud and over time turned into rock
    22. 22. Fossil Evidence • Fossils are when a dead animal or plant is buried in mud and over time turned into rock • Fossils have been found of animals and plants which are extinct
    23. 23. Fossil Evidence • Fossils are when a dead animal or plant is buried in mud and over time turned into rock • Fossils have been found of animals and plants which are extinct • Fossils give us an idea of how animals and plants looked in the past (and in many cases they are different now)
    24. 24. Horses
    25. 25. Horses • The evolution of the horse was not in a “straight line” from Eohippus to what we know now
    26. 26. Horses • The evolution of the horse was not in a “straight line” from Eohippus to what we know now • There were many “branches” in the family tree
    27. 27. Horses • The evolution of the horse was not in a “straight line” from Eohippus to what we know now • There were many “branches” in the family tree • The other species were not adapted to their environment and so they became extinct
    28. 28. Bacteria
    29. 29. Bacteria • Bacteria reproduce very quickly
    30. 30. Bacteria • Bacteria reproduce very quickly • Bacteria are killed by antibiotics
    31. 31. Bacteria • Bacteria reproduce very quickly • Bacteria are killed by antibiotics • If a bacterium survives then its offspring will also survive the same antibiotics
    32. 32. Bacteria • Bacteria reproduce very quickly • Bacteria are killed by antibiotics • If a bacterium survives then its offspring will also survive the same antibiotics • The only bacteria left are not killed by antibiotics
    33. 33. Bacteria • Bacteria reproduce very quickly • Bacteria are killed by antibiotics • If a bacterium survives then its offspring will also survive the same antibiotics • The only bacteria left are not killed by antibiotics • Bacteria become “resistant” to antibiotics
    34. 34. Questions • What does “adaptation” mean? • What does “competition” mean? • What factors prevent offspring from surviving to the next generation? • How do animals and plants “adapt” to their environment?
    35. 35. Homework • Biology For Mon 17th May • Write 200 words about how to prevent bacteria from becoming resistant to antibiotics • (Useful Google search terms: MRSA, C difficile, antibiotic resistance, hospitals)

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