02c types of natural selection

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  • 02c types of natural selection

    1. 1. Types of Natural Selection
    2. 2. Think. Pair. Share. What are the driving factors for the evolution of a beetle from small and brown to larger, red, and spotted?
    3. 3. Types of Natural Selection
    4. 4. Types of Natural Selection
    5. 5. Types of Natural Selection
    6. 6. Types of Natural Selection
    7. 7. Types of Natural Selection
    8. 8. Types of Natural Selection
    9. 9. Types of Natural Selection In some environments, a species may face one or many selective pressures.
    10. 10. Types of Natural Selection A selective pressure may increase or decrease the survival and reproduction rate of certain traits. Weed killer is a selective pressure.
    11. 11. Types of Natural Selection New population Why do they not die?
    12. 12. Types of Natural Selection Evolution
    13. 13. Types of Natural Selection Examples include climate, food availability, and predators.
    14. 14. Types of Natural Selection There are 4 types of Natural Selection: 1) Directional Selection 2) Stabilizing Selection 3) Disruptive Selection 4) Sexual Selection
    15. 15. Types of Natural Selection Suppose a certain mouse population has a range of fur colours, from light brown to dark brown.
    16. 16. Directional Selection 1) Directional selection occurs when a selective pressure favours an extreme variation of a trait.
    17. 17. Directional Selection For example, the surrounding woody environment may provide better camouflage for darker mice, thus most of the lighter colour mice may be easily hunted.
    18. 18. Stabilizing Selection 2) Stabilizing selection occurs when a selective pressure favours the average phenotype.
    19. 19. Stabilizing Selection For example, a new predator may only be able to see vivid colours (like white and dark brown), allowing the dull brown mouse to avoid detection and escape.
    20. 20. Disruptive Selection 3) Disruptive selection favours extreme traits for survival while the average phenotype declines.
    21. 21. Disruptive Selection For example, predators may not eat the vividly coloured mice in the area because the other white and dark brown creatures in the area are toxic.
    22. 22. Sexual Selection 4) Sexual selection favours traits that increase the success for an organism to find a mate and reproduce.
    23. 23. Sexual Selection Usually involves (female) mate choice or (male versus male) competition. Examples: Peacock Satyr tragopan (video) Bighorn rams (video)
    24. 24. Sexual Selection Sexual Dimorphism is the difference of phenotypes between males and females of the same species. These are the traits often used in sexual selection. Examples include: - Colour - Height - Size of a particular feature (such as horns or tusks)
    25. 25. Sexual Selection The satyr tragopan displays its blue horns and wattle to attract females.

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