evolution 7

• Evolution

  The changes in organisms over generations as a result of genomic variations
• Natural selection

  The non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious alleles
• Horizontal gene transfer


  Where genes are transferred between individuals of the same generation
• Vertical gene transfer

  Where genes are transferred from parent to offspring as a result of sexual or asexual reproduction
• Natural selection is more rapid in prokaryotes
• Prokaryotes can exchange material horizontally, resulting in a faster evolutionary change than in organisms that only use vertical transfer
• Species


  A group of organisms capable of interbreeding and producing fertile offspring, which does not normally breed with other groups
• Speciation


  The generation of new biological species by evolution as a result of isolation, mutation and selection
• Allopatric speciation

  Geographical barriers lead to this
• Allopatric speciation


  • Lakes drying out and volcanic eruptions
• Sympatric speciation


  Behavioural and ecological barriers lead to this
• Sympatric speciation


  • Behavioural - slight change in mating call such as pitch or tone
  • Ecological - Difference in flowering time of plants