Gr 11 Artificial Selection

Selective breeding of domesticated animals shows that artificial selection can cause evolution

Humans have deliberately bred and used particular animal species or thousands o years. I modern breeds o livestock are compared with the wild species that they most resemble, the dierences are oten huge. Consider the dierences between modern egg-laying hens and the jungleowl o Southern Asia, or between Belgian Blue cattle and the aurochs of Western Asia. There are also many dierent breeds o sheep, cattle and other domesticated livestock, with much variation between breeds.

It is clear that domesticated breeds have not always existed in their current orm. The only credible explanation is that the change has been achieved simply by repeatedly selecting or and breeding the individuals most suited to human uses. This process is called arti€cial selection.

The eectiveness o arti€cial selection is shown by the considerable changes that have occurred in domesticated animals over periods o time that are very short, in comparison to geological time. It shows that selection can cause evolution, but it does not prove that evolution o species has actually occurred naturally, or that the mechanism or evolution is natural selection.

Selective breeding is a form of artificial selection, whereby man intervenes in the breeding of species to produce desired traits in offspring

• By breeding members of a species with a desired trait, the trait’s frequency becomes more common in successive generations
• Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a (relatively) short period

Selective breeding of plant crops has allowed for the generation of new types of foods from the same ancestral plant source

• Plants of the genus Brassica have been bred to produce different foods by modifying plant sections through artificial selection
• This includes broccoli (modified flower buds), cabbage (modified leaf buds) and kale (modified leaves)

Selective breeding of domesticated animals has also resulted in the generation of diverse breeds of offspring

• Examples of selective breeding of domesticated animals can be seen in horse, cows and dogs

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