Selective Breeding

orArtificial Selection

What is Selective Breeding?

Selective breeding is the process of breeding plants and animals for particular traits. The term selective breeding is synonymous with artificial selection.

This selection process is "artificial" when human preferences for specific traits have a significant effect on the changes in a particular population or species.

Domestication and Selective Breeding

Domestication is the process whereby a population of animals or plants, through a process of artificial selection, is changed at the genetic level, accentuating traits desired by humans.

It differs from taming in that a change in the genetics and physical traits of the animal occurs. Taming is the process by which animals become used to the presence of humans.

Historical Support for Selective Breeding

Charles Darwin wrote how selective breeding had been successful in producing change over time in his book, On the Origin of Species.

The first chapter of the book discusses selective breeding and domestication of such animals as pigeons, dogs, and cattle.

Selective breeding was used by Darwin as a way to introduce the theory of natural selection and to support it.

Selective breeding tries to establish and maintain certain stable traits that animals will pass to the next generation.

These are traits that humans find desirable in domesticated species such as disease resistance, strength, calmness, more lean meat, endurance, etc.

In many cases this makes the species stronger.

Advantages of Selective Breeding

Breeding from too small a gene pool can lead to the passing on of undesirable characteristics or even a collapse of a breed population due to what is called inbreeding depression.

Breeding for only one trait, over all others, can cause problems. For example, certain roosters bred for fast growth or heavy muscles did not know how to perform the typical rooster courtship dance. The dance bonds the roosters to the hens. No mating dance led the roosters to kill the hens after reproducing with them.

This is not a trait which encourages survival of the species!

Disadvantages of Selective Breeding

Examples of Selective Breeding

Carrots in a variety of colors

Variegated ears of maize (Indian corn)

Examples of Selective Breeding

Examples of Selective Breeding

Charolais cattle produce beef that has more red meat and less fat.

Examples of Selective Breeding

Chihuahuas and Great Danes are bred for size.

Selective Breeding and Natural Selection

The main difference between natural selection and selective breeding is human involvement.

In natural selection, the reproduction of organisms with certain traits is attributed to improved survival or reproductive ability (survival of the fittest).

In artificial selection, humans favor specific traits and control breeding for those traits.