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Artificial Selection�AP Topic 7.3

  • Learning Objectives
    • Explain how humans can affect diversity within a population.
    • Explain the relationship between changes in the environment and evolutionary changes in the population.

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AP BIOLOGY

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Humans affect variation �in other species

  • artificial selection
    • the process by which humans selectively breed organisms with desired traits
    • contrast with natural selection
      • environmental pressures guide evolution
    • examples: domesticated plants and animals

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AP BIOLOGY

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Humans Affect Biological �& Genetic Diversity

  • selective breeding
    • favoring specific traits reduces genetic variation
      • examples: dog breeds, cattle, crops (corn, wheat)

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AP BIOLOGY

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Humans Affect Biological �& Genetic Diversity

  • genetic engineering (GMOs)
    • direct modification of DNA for desired traits
    • examples: Bt corn (pest resistance) & golden rice (vitamin A)

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AP BIOLOGY

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Humans Affect Biological �& Genetic Diversity

  • monoculture & reduced genetic diversity
    • large-scale farming with single genetic variants
    • susceptibility to diseases
      • e.g. Irish potato famine

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AP BIOLOGY

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Humans Affect Biological �& Genetic Diversity

  • overhunting, overfishing, overharvesting
    • reduction in population sizes affects genetic diversity
    • Examples:
      • elephant tusks
      • cod fishery collapse

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AP BIOLOGY

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Case Study:�Domestication of Dogs

  • wolves → dogs
  • selective breeding for behavior, coat type, and size
  • over 340 breeds with varied traits but reduced genetic diversity

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AP BIOLOGY

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Human Induced Natural Selection & Environmental Pressures

  • human caused environment changes
    • different traits may become beneficial
    • example: industrial melanism – peppered moths
  • human impact on the environment
    • species adapt or go extinct
    • example - climate change
          • coral bleaching
          • habitat destruction

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AP BIOLOGY

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Consequences �of Artificial Selection

  • reduced fitness
  • loss of beneficial genes in populations
  • superbugs (pathogens) & antibiotic resistance
    • bacteria evolve resistance due to overuse of antibiotics
      • example: MRSA (methicillin-resistant staphylococcus aureus).
  • herbicide & pesticide resistance
    • weeds and pests evolving resistance to chemicals

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AP BIOLOGY

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Summary �Artificial Selection (7.3)

  • Artificial selection is contrasted with natural selection
    • Humans (rather than environmental pressure) select favorable traits
  • Impacts
    • decreases genetic diversity but enhances certain traits
    • human activities can drive evolutionary changes, sometimes unintentionally.
    • human environmental change influences the survival and traits of populations
      • can lead to negative evolutionary consequences

7 Natural Selection & Evolution

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AP BIOLOGY

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