bio

• Mutation

  A random change to a genetic material
• Possible effects of mutations

  • Neutral
  • Confer an advantage
  • Confer a disadvantage for survival
• Mutagenic agents

  • Radiation (e.g. gamma rays, x-rays)
  • Some chemicals (e.g. nicotine, mustard gas)
• Mutations are spontaneous and the only source of new alleles, which increase variation
• New alleles produced by mutation

  Can result in plants and animals becoming better adapted to their environment
• Adaptation

  An inherited characteristic that makes an organism well-suited to survival in its environment
• Examples of adaptations

  • Behaviour
  • Body structure
• Variation within a population makes it possible for a population to evolve over time in response to changing environmental conditions
• Natural selection

  Survival of the fittest due to selection pressures such as competition for limited resources
• Examples of selection pressures

  • Disease
  • Predators
  • Competition for food, space, mate
  • Change in climate
• Speciation

  The formation of a new species
• Stages of speciation

  • Isolation barriers
  • Mutation
  • Natural selection
• Species

  A group of organisms that can interbreed and produce fertile offspring
• Types of isolation barriers

  • Geographical
  • Ecological
  • Behavioural
• Isolation barriers

  Prevent the exchange of genes from one population to another
• Different mutations occur in each new subpopulation

  Due to lack of gene flow between subpopulations
• Natural selection selects for different mutations

  In each subpopulation due to different selection pressures
• Over many generations

  Subpopulations evolve to become different species