Selective breeding

Selective breeding has transformed food crops — they’re bigger, tastier and more attractive. But the process has its downsides.

 
 
Selective breeding has completely changed most of the food we are now familiar with. Wild bananas (pictured above) were much smaller with large, hard seeds. Selective breeding over thousands of years has resulted in the longer, fruitier bananas with…

What bananas looked like before selective breeding. Credit: Eric Danell

Artificial selection

Selective breeding is a process which is carried out by people to improve characteristics in plants and animals, usually for human benefit. As this process is carried out by humans, rather than nature, it is referred to as artificial selection.

Organisms can be selectively bred for the following features:

  • Increased meat or milk production

  • Larger eggs

  • Larger fruit

  • Resistance to disease

  • Increased nutritional content

  • Calm temperament

Method of selective breeding

Selective breeding is a long process which results in gradual changes to a species with each successive generation.

It is carried out in the following way:

  1. A male and female organism are selected which display the desired characteristic (e.g. high meat production)

  2. The parents are bred together to produce offspring

  3. The offspring which also display the desired characteristic are selected and bred together.

  4. This process is repeated over many generations

Problems with selective breeding

As selective breeding involves a lot of inbreeding, the offspring are genetically similar so are equally vulnerable to the same diseases. Inbreeding can also result in loss of alleles from a population, making it difficult to produce different varieties of plants or animals in the future.

Selective breeding for certain traits can often result in adverse health problems.

For example, certain dog breeds have been selectively bred to produce cuter puppies with more exaggerated features. Inbreeding of dog breeds such as pugs and French bulldogs to achieve squashed noses has resulted in blocked airways and breathing difficulties.