Speciation & Selection

Allopatric Speciation
1. Geographical isolation
  1. Reproductively isolated
  2. physical barrier prevents two population from breeding.
  3. Such as oceans, rivers and deserts.
2. Variation between the original Species
3. No gene flow between the two groups
4. Environments are different, so natural selection favour different characteristics
5. Allele frequencies change
  1. Eventually the population becomes unable to interbreed
is the evolution of new species from existing species
Selection is the process by which organisms that are better adapted to their environment survive and breed.
1. Directional
  1. selection may favour individuals that vary in one direction from the mean of the population.
2. Stabilising
  1. Selection may favour average individuals
Mutation creates variation
1. Individuals with an advantageous allele survive to reproduce in greater numbers than other types.
2. They pass their advantageous allele to their offspring in greater numbers
3. The frequency of the advantageous allele in the population increases in the next generation.

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