Selections

• What is genetic diversity?

  • The number of different alleles of genes in a population.
• What is a population?

  • A population is a group of individuals of the same species that live in the same area and can interbreed.
• What is a species?

  • A species is a group of individuals with similar characteristics that can breed to produce fertile offspring.
• Natural selection is not possible without genetic variation.
• What is directional selection?

  • An environmental change that produces a new selection pressure that favours organisms with an extreme form of a characteristic.
• In directional selection the mean changes (shifting left or right on the X-axis) but the standard deviation of the sample stays the same.
• What is stabilising selection?

  • Due to a stable environment natural selection favours the 'average' members of a population.
  • Due to this there are more individuals at the mean so the mean doesn't change.
  • However, the standard deviation decreases resulting in extreme characteristics being selected against preserving the mean characteristics of the population.