Genetic diversity/adaption

• Population

  All the organisms of a particular species that live in the same place
• Allele


  Different forms of a particular gene, found at the same locus (position) on a chromosome. A single gene could have many alleles
• Genetic diversity


  The total number of different alleles in a population
• Advantage of high genetic diversity

  • Ability to adapt to a change in environment; allows natural selection to occur
• How natural selection results in development of new characteristics

  1. Random mutations result in new alleles

  2. Some alleles provide an advantage, making an individual more likely to survive and reproduce

  3. Their offspring receive the new allele, and frequency continues to increase over many generations
• Directional selection

  Occurs when environmental conditions change. Individuals with phenotypes suited to the new conditions will survive and pass on their genes. Over time the mean of the population will move towards these characteristics
• Directional selection

  • Antibiotic resistance. Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce. Therefore frequency of this allele will increase and the population will shift to have greater antibiotic resistance
• Stabilising selection

  Occurs when environmental conditions stay the same. Individuals closest to the mean are favoured, and any new characteristics are selected against. Results in low diversity
• Stabilising selection

  • Birth weight; babies that weigh around 3kg are more likely to survive than those at lower or higher weights
• Niche


  The role of a species within its environment. Species sharing the same niche will compete with each other
• Types of adaptation

  • Anatomical (changes to body structure) e.g. oily fur
  • Physiological (changes to bodily processes) e.g. venom production
  • Behavioural (changes to actions) e.g. hibernation