Evolution

• Biodiversity is the number of different species thag exist on this planet
• Mutations are changes in the sequence of DNA in a chromosome or gene
• When mutations build up they can reproductively isolate one population from another leading to speciation(new species forming)
• Evolution is the gradual genetic change that occurs in organisms over time
• Evolution of the 'Theory of Evolution'

  • 1829-Lamark: organisms accquired traits and passed them onto their offspring
  • 1858-Russel Wallace +Darwin: Natural Selection
• The theory of evolution by natural selection:

  Observation - 1.species overbreed, population remains constant 2.individuals are variable

  Conclusion: 1.most organisms dont survive

  2.those that survive are better adapted and pass on their adaptations to their offspring
• Evidence for evolution

  • Fossil record
  • Comparative genes
  • Direct observation
  • Comparative biochemistry
• Examples of natural selection

  Peppered moth

  • Dominant pale form, as they camouflaged and outnumbered dark ones
  • Industrial revolution caused trees to be black- dark moths increased & pale declined
  • Clean Air Act removed the pollution and the tree trunks were paler, pale moths increased and dark declined

  Darwin's Finches

  • A seed-eating species got blown over to Galapagos
  • An empty archipelago island had many vacant places
  • The finches spread out so much new species developed
  • Some are still seed-eaters, some insects, 1 developed a taste for blood, 1 eats fruit and 1 only lives in mangroves