Selection acts on phenotypic characters whatever their origin, and can retain or eliminate the characters' genetic basis. Artificial selection is any selective breeding intentionally practiced by humans leading to the evolution of domesticated organisms. Artificial selection may oppose or amplify or be neutral in relation to natural selection. Most livestock, including dogs, cats, goats, pigs, cattle, sheep, guinea pigs, horses, geese and poultry and scores of crop plants were domesticated more than 5000 years ago. (Estimates of dates of domestication based upon the archaeological record differ enormously from those based on genetic analysis for almost all crops and livestock. However, experts agree that dogs were among the first mammalian species to become domesticated, followed by sheep.) During the last few hundred years, people have domesticated a wide range of other animals such as guppies, hamsters, mice and budgerigars, mostly for use as pets, together with thousands of culinary, medicinal and ornamental plants.

An example of artificial selection - Dog breeding

Nowadays, these domesticated animals are what we call dogs! Domestication is the act of separating a small group of organisms (wolves, in this case) from the main population, and select for their desired traits through breeding.