SPECIATION REV SHEET

i copied this off the cgp aqa book, onto word so it is more clear and easier to revise. I find it useful to print out and highlight key points, hope it helps!

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  • Created on: 28-10-12 21:53
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Speciation
SPECIATION is the development of a NEW SPECIES.
. A species is a group of similar organisms that can reproduce to give
fertile offspring
. Speciation is the development of new species
. Speciation occurs when populations of the same species become so
different that they can no longer breed together to produce fertile
offspring
Isolation and Natural Selection Lead to Speciation
. Isolation is where populations of a species are separated. This can
happen due to a physical barrier e.g. floods and earthquakes can cause
barriers that geographically isolate some individuals from the main
population.
. Conditions on either side of the barrier are slightly different (e.g.
different climates) because the environment is different on each side
different characteristics will become more common in each population
due to natural selection.
1. Each population shows variation because they have a wide range of
alleles
2. In each population individuals with characteristics that make them
better adapted to their environment have a better chance of survival
and so are more likely to breed successfully.
3. So the alleles that control the beneficial characteristics are more likely to
be passed on to the next generation
Eventually individuals from the different populations would have changed
so much that they won't be able to breed with one another to produce
fertile offspring. The two groups have become separate species.

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