Artificial Selection

Artificial Selection

• Humans deliberately breed together organisms with desired traits.

• They provide an artificial “selection pressure”.• This can lead to a great divergence from

“wildtype” traits.• Traits that are non-adaptive in the wildtype

may be expressed in the domestic version.

Importance of Domestication• Allowed for agriculture and hence to ability to settle down (as

opposed to being nomadic).• Being able to settle allowed more time to develop technology.• It has allowed human to produce crops that:

– produce a higher yield per area (e.g. larger grains, more per plant)– Are easier to process (e.g. seeds come away from stem more easily,

wheat easy to separate from chaff).– Put more energy into building edible parts.

• It has lead to the development of animals that:– Are easier to handle.– Provide transport or move goods.– Beast of burden (to help til the soil or grind grain)– Animals that can assist human (such as hunting dogs, sheep dogs etc.)

Examples of artificial selection

• Domestication of: wolves, cats, horses, cows, chickens, pigeons etc.

• Wheat, corn, mustard plants, apples, ornamental flowers.

• Accidental artificial selection: bacteria that become resistant to antibiotics, smaller fish

Mustard family

The Mustard Family

Corn

Wheat