• Created by: India.02
  • Created on: 30-05-19 15:08


- A species is a group of similar organisms that can reproduce to give fertile offspring

- Speication is the developmetn of a new species

- Speciation occurs when populations of the same species become so different that they can no longer successfully interbreed to produce fertile offspring

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Result of Isolation and Natural Selection

- Isolation is where populations of species are separated - can happen due to a physical barrier (floods or earthquakes can barriers that geographically isolate populations)

- Conditions on either side of the barrier will be different (climates)

- Since the environment is different on each side, different characteristics will become more common in each population due to natural selection operating differently on the populations

-Each population shows genetic variation because they have a wide range of alleles - in each population, individuals with characteristics that maek them better adapted to survive in their environment will have a better chance of breeding successfully - alleles that control the beneficial characteristics are more likely to be passed on to the next generation

- Eventually, individuals from the different populations will have changed so much that they won't be able to breed with one another to produce fertile offspring

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Wallace and The Theory of Speciation

- Alfred Russel Wallace was a scientist working at the same time as Charles Darwin - he was one of the early scientists to work on the idea of speciation and contribute ideas that we use to understand the concept

- He independently came up with the idea of natural selection and published his work on the subject together with Darwin in 1858 - this then prompted Darwin to write 'On the Origin of Species' in 1859

- Observations made by Wallace on his travels provided lots of evidence to support the theory of evolution by natural selection

- He realised that warning colours are used by some species to deter predators from eating them - this was an example of a beneficial characteristic that had evolved by natural selection

- The work on warning colours and his work on speciation is what he is most famous for

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