Natural Selection


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•  Natural selection increases the frequency of characteristics that make individuals better adapted and decreases 

    the frequency of other characteristics leading to changes within the species

The theory of natural selection was posited by Charles Darwin (and also Alfred Wallace) who described it as ‘survival of the fittest’

  • According to this theory, it is not necessarily the strongest or most intelligent that survives, but the ones most responsive to change

The process of natural selection occurs in response to a number of conditions:

  • Inherited Variation – There is genetic variation within a population which can be inherited
  • Competition – There is a struggle for survival (species tend to produce more offspring than the environment can support)
  • Selection – Environmental pressures lead to differential reproduction within a population
  • Adaptations – Individuals with beneficial traits will be more likely to survive and pass these traits on to their offspring
  • Evolution – Over time, there is a change in allele frequency within the population gene pool

Process of Natural Selection

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Natural Selection Mnemonic

ice age

The key components to the process of natural selection are:

  • Inherited variation exists within the population
  • Competition results from an overproduction of offspring
  • Environmental pressures lead to differential reproduction
  • Adaptations which benefit survival are selected for
  • Genotype frequency changes across generations
  • Evolution occurs within the population

Mnemonic:  ICE AGE

Overview of Natural Selection