Biology, gcse aqa B2 6.4

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  • Biology- isolation and the evolution of new species.
    • Isolation and evolution
      • If the popualtion gets seperated the conditions are likely to be different, this means different characteristics will be selected to help that population survive
      • Any population of a species has gentic variation.
      • once the species can no longer interbreed, a new species has been formed.
    • How do populations become isolated.
      • Geographical isolation- they become physically isolated by a geographical feature. This might be a new mountain range, a new river or land becoming an island.
        • When Australia seperated from the rest of the continents 5 million years ago, mammals started to carrry their babies in pouches.
    • Organisms in isolation.
      • If organisms are only on one island then they are called endemic to that place.
    • Speciation!
      • Genetic variation is caused by sexual reproduction and mutation.
      • The allels that will be selected are the ones that help the species to survive.
      • The alleles selected will change depending on the environment, when a species can no longer interbreed with the old species, speciation has taken place.


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