Old and new species key points

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  • Created by: millera
  • Created on: 23-03-14 11:45
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  • old and new species
    • Origins of life on earth
      • Fossils are the remains of organisms from many years ago that are found in rocks
      • Fossils may be formed in different ways
      • Fossils give us information about organisms that lived millions of years ago
      • It is very difficult for scientists to know exactly how life on earth began because there is little evidence
    • Exploring fossil evidence
      • Causes of extinction
        • New predators
        • New diseases
        • New or more successful competitors
      • What we learn from fossils
        • How much or how little organisms have changes
    • Extinction
      • Caused by
        • Environmental change over geological time
      • Mass extinction
        • Caused by
          • Single catastrophic events
            • e.g Volcanoes or asteroid strikes
    • Isolation and evolution of new species
      • New species arise when two populations become isolated
      • Populations become isolated when they are separated geographically
        • e.g. on Islands
      • There are natural cycles linked to environmental change when species from and when species die out
      • In an isolated population alleles are selected that increase successful breeding in the new envrionment.
      • Speciation
        • Takes place when an isolated population becomes so different from the original population that the successful interbreeding can no longer take place


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