Genetic diversity and natural selection

• What is Genetic Diversity?

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


  The process that leads to evolution in populations. It results in species becoming better adapted to their environment.
• What are the 3 types of adaptation?

  1. Behavioural
  2. Physiological
  3. Anatomical
• What is evolution?

  The change in allele frequency over many generations in a population.
• What is the process of natural selection?

  • Random mutations introduce a new allele.
  • This advantageous alle increases chances of survival, so individual will survive and reproduce.
  • This passes on the advantageous allele onto the next generation.
  • This increases the allele frequency over many generations.
• What is directional selection?

  • One of the extremes has the selective advantage
  • This occurs when there is a change in the environment.
  • Modal trait changes.
  • e.g.-antibiotic resistance in bacteria.
• What is stabilising selection?

  • favours the average(modal) phenotype.
  • occurs when there is no change in the environment.
  • standard deviation decreases as individuals with the extreme trait decrease.
  • e.g. human birth weights.