Old and New species

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  • Created by: Moodymoo
  • Created on: 09-02-14 13:51
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  • Old and New Species
    • Fossils
      • Fossils are the remains of organisms from many years ago
      • Formed from hard parts of an animal, e.g. bones
      • When an animal/ plant doesn't decay after it dies due to a lack of a condition needed for decay, e.g. low temperature
      • Formed when harder parts of animal/plant are replaced by minerals, most common fossils
      • Traces animals/plants leave behind, e.g. footprints, droppings
    • Incomplete Record
      • Many of the earliest forms of life were soft-bodied organisms, so have little fossil trace
        • Partly why there is little valid evidence why earth began
    • Using the Fossil Record
      • Helps us understand how much fossils have changed
      • However, only bits of skeleton have been found
      • They show us that not all animals have changed very much, e.g. sharks
    • Extinction
      • The permanent loss of a species
      • As conditions change, new species that are better suited to the environment survive
        • Old species cant cope with the new conditions die out
    • Organisms that cause Extinction
      • New predators can wipe out unsuspecting prey quickly
      • New diseases (caused by microorganisms) cause it
      • Through successful competition, e.g. competing for food
    • Environmental Changes
      • Climate and environment on Earth has changed
      • Many species become extinct through lack of food or being too cold to breed
      • Mass extinctions, most species die out
    • Isolation and Evolution
      • Populations become isolated when they are separated geographically e.g. on islands
        • The species might change so much that they can no longer interbreed
      • Speciation
        • Populations contain genetic variety, so contains a lot of alleles controlling characteristics
        • When two populations can no longer interbreed, become two different species


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