evolution of a species

• a mutation is a random change in an organisms genetic material
• mutations are spontaneous but mutagenic agents such as chemicals and radiation can increase the rates
• mutations increase variation#
• adaption is an inherited characteristic making an organism better suited to survival in its niche
• natural selection is the process which choses charactersistic best suited to an organisms survival
• natural selection - species produce more offspring than the

  environment can support

  - best adapted individuals survive selection

  pressures

  - survivors produces and pass on favoured

  alleles with selective advantage

  - favoured alleles increase in frequency
• speciation is the process by which a new species is formed
• speciation - isolation - population split by isolation barrier

  - mutation - different + random mutations occur

  potentially giving a selective advantage

  - natural - diff selection pressures , each subpopulation

  selection evolves until they are so genetically different

  forming a new species
• selection barriers - geographical - rivers , oceans ,mountains

  - ecological - PH , temp , humidity

  - behavioural - different mating behaviours