B2 6.4 Isolation and the evolution of new species

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Learning Objectives and Key points

How do new species arise?

New species arise when two populations become isolated.

1. Isolation: Two populations of a species become isolated (e.g. geographically)

2. Genetic variation: Each population has a wide range of alleles that control their characteristics. Any population of living organisms contain genetic variety.

3. Natural selection: The conditions the populations that have been isolated in are likely to be different. In each population, the alleles that control the characteristics which help the organism to survive and adapt are selected. Different characteristics will be selected for each population.

4. Speciation: The populations become so different that succesful interbreeding is no longer possible and a new species evolves.

How do populations become isolated?

The most common way for populations become isolated is when they are seperated geographically. This is when two populations become isolated by a geographically feature e.g. a new


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