Key area 6 - Evolution of species

• Mutation

  A random change to genetic material
• Possible outcomes of inheriting a mutation

  • nuetral
  • Confer a Disadvantage
  • Confer a Advantage
• Environmental factors that can increase the rate of mutation

  • Radiation
  • Chemicals
• Adaptation

  A inherited characteristic that makes an organism well suited to survival in its environment or niche
• Types of isolation barrierand examples of them

  • Geographical - rivers, mountains
  • Ecological - ph, salinity
  • Behavioral - different breeding times
• Isolation barriers lead to speciation
• Why are mutations important

  They are the only source of new alleles
• What does variation within a population allow

  Makes it possible for a population overtime to evolve in response to changing environmental conditions
• describe the role that natural selection plays in speciation

  kills all of the organisms that are not fit to survive - they have unfavourable genes
• Define Natural Selection

  It happens when only the fittest of the population can survive natural selection because of sub-populations experiencing different selection pressures. The best adapted individuals survive and reproduce to pass on their favourable alleles that confer a selective advantage. These alleles increase in frequency within the population until all the population have these alleles
• Why are mutation important

  they are the only source of new alleles