Selective breeding

• Selective breeding is an artificial process in which organisms with desired characteristics are chosen as parents for the next generation
• Humans have bred food crops from wild plants and domesticated animals for thousands of years
• Main steps involved in selective breeding:

  • Decide which characteristics are important to select
  • Choose parents that show these characteristics from a mixed population and breed them together
  • Choose the best offspring with the desired characteristics to produce the next generation
  • Repeat the process continuously over many generations until all offspring show the desired characteristics
• Desired characteristics in plants:

  • Disease resistance in food crops
  • Wheat plants that produce lots of grain
  • Large or unusual flowers
• Desired characteristics in animals:

  • Animals that produce lots of milk or meat
  • Chickens that lay large eggs
  • Domestic dogs that have a gentle nature
• Benefits of selective breeding:

  • New varieties may be economically important by producing more or better quality food
  • Animals can be selected that cannot cause harm, for example cattle without horns
• Risks of selective breeding:

  • Reduced genetic variation can lead to attack by specific insects or disease, which could be extremely destructive
  • Rare disease genes can be unknowingly selected as part of a positive trait, leading to problems with specific organisms
  • Can create physical problems in specific organisms, for example, large dogs can have faulty hips due to not being formed correctly