selective breeding

Selective breeding (also called artificial selection) is the process by which humans breed other animals and plants for particular traits. Typically, strains that are selectively bred are domesticated, and the breeding is normally done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties, cultigens, or cultivars. The cross of animals results in what is called a crossbreed, and crossbred plants are called hybrids.
In animal breeding techniques such as inbreeding, linebreeding, and outcrossing are utilized. In plant breeding, similar methods are used. Charles Darwin discussed how selective breeding had been successful in producing change over time in his book, Origin of Species. The first chapter of the book discusses selective breeding and domestication of such animals as pigeons, cats, cattle, and dogs. Selective breeding was used by Darwin as a springboard to introduce the theory of natural selection, and to support it.[1]
The deliberate exploitation of selective breeding to produce desired results has become very common in agriculture and experimental biology.
Selective breeding can be unintentional, e.g. resulting from the process of human cultivation; and it may also produce unintended - desirable or undesirable - results. For example, in some grains, an increase in seed size may have resulted from certain ploughing practices rather than from the intentional selection of larger seeds. Most likely, there has been an interdependence between natural and artificial factors that have resulted in plant domestication.[2]

Selective breeding of both plants and animals has been practiced since early prehistory; key species such as wheat, rice, and dogs have been significantly different from their wild ancestors for millennia, and maize, which required especially large changes from teosinte, its wild form, was selectively bred in Mesoamerica. Selective breeding was practiced by the Romans.[3] Treatises as much as