Selection

Selection

Definition

  • Selection is a key process in evolution and can be either natural or artificial.
  • It involves the differential survival and reproduction of individuals due to differences in their traits.
  • The natural version of this process operates wherever there is heritable variation in fitness, while artificial version is driven by human choice.

Natural Selection

  • Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring.
  • Charles Darwin, a 19th-century naturalist, proposed this as an explanation for adaptation and speciation.
  • It is summed up by the phrase “survival of the fittest” - where “fit” refers to an organism’s ability to pass on its genes to the next generation.
  • The process of natural selection involves variation, competition, and inheritance. Variations advantageous to survival allow organisms to compete more effectively, and these traits are then inherited by future generations.

Artificial Selection

  • Artificial selection, on the other hand, involves humans selectively breeding plants and animals with desired traits.
  • It has been instrumental in the development of different varieties of domesticated animals and crops.
  • With artificial selection, traits that might not necessarily be advantageous for survival, but are favoured by humans, become more common.
  • The result can be striking physical differences from the organism’s wild ancestor - consider the many different breeds of dogs, all descended from a common ancestor.

Examples of Selection

  • The peppered moth provides a classic example of natural selection in action. Before the Industrial Revolution, light-coloured moths were more common, but as pollution darkened tree bark, dark-coloured moths became more common as they were better camouflaged.
  • In terms of artificial selection, the development of different dog breeds provides a clear example. Through selective breeding, humans have created a huge range of dogs, from small and hairy Chihuahuas to large and smooth-skinned Great Danes - all from a common ancestor.

Selection and Evolution

  • Both forms of selection, natural and artificial, result in evolutionary changes within a species.
  • Over time, favourable traits become more common within a population – in other words, the population ‘evolves’.
  • The principles of natural selection underpin modern theories of evolution and provide an explanation for the diversity of life on Earth.