Evolution of species

• Passing on the favourable alleles that confer the selective advantage

  Increase in frequency within the population
• Mutations are spontaneous and can be caused by environmental factors
• Environmental factors that can create the rate of mutation

  • Gamma rays
  • X-rays
  • Radioactive material
  • Mustard gas
  • Tobacco smoke
• These increase the organism's chances of survival in its environment
• Mutations may be neutral, confer an advantage or a disadvantage to survival
• Natural selection or survival of the fittest occurs when there are selection pressures (limited resources)
• Variation within a population arises from new alleles produced by mutation
• Individuals best adapted to a population

  Survive and reproduce
• Species produce more offspring than the environment can sustain
• New alleles produced by mutation can result in plants and animals becoming better adapted to their environment
• Variation


  Arises from new alleles produced by mutation
• Survive and reproduce

  Passing on the favourable alleles that confer the selective advantage
• Mutation


  A random change to genetic material
• Environmental factors that can create the rate of mutation

  • Radiation
  • Some chemicals
• Mutations are the only source of new alleles
• Speciation

  1. A population becomes isolated by an isolation barrier

  2. Different mutations occur in each sub-population

  3. Natural selection selects for different mutations in each group

  4. Each sub-population evolves until they become so genetically different they are two different species
• Speciation


  The formation of new species