Selective breeding

• What is selective breeding?

  An artificial process in which organisms with desired characteristics are chosen as parents for the next generation
• How long have humans been using selective breeding?

  Thousands of years
• For what purpose do people selectively breed animals and plants?

  • Desirable traits e.g. higher crop yields, better disease resistance, improved appearance (pets)
  • Improved crop quality e.g. better taste, nutritional content, larger size
  • Behavioural traits e.g. pets that are calm, easy to train, intelligent
• How does selective breeding affect the gene pool?

  It reduces the gene pool of a population
• What is a gene pool?

  The collection of alleles in a population
• What is the consequence of repeatedly selecting for certain alleles?

  It leads to a smaller pool of alleles
• Why can inbreeding be a problem in selective breeding?

  It makes offspring prone to diseases and defects
• What dog breeds are mentioned as prone to health conditions due to selective breeding?

  German shepherds and rottweilers
• What is a risk of having a small gene pool in a population?

  Increased vulnerabilty to diseases
• What could happen if a new pathogen infects a selectively bred crop?

  The entire crop could be lost at once
• What are the steps involved in the process of selective breeding?

  1. Identify individuals with desired traits
  2. Breed selected individuals together
  3. Evaluate offspring for desired traits
  4. Repeat the process over generations
• What are the advantages and disadvantages of selective breeding ?

  Advantages:

  • improved traits in plants and animals
  • increased productivity

  Disadvantages:

  • Reduced genetic diversity
  • Increased risk of diseases and defects