Artificial Selection means intentionally breeding for certain traits, or combination of traits. Artificial is a term that utilized by Charles Darwin to contrast natural selection. We have been taking advantage from this. We produce plants and animals that satisfy our need and want. For example, animal breeders are often able to change the characteristics of animals by selecting those individuals with the most desirable qualities to reproduce such as milk production in cows, trail scenting in dogs.
What are the reasons for artificial selection?
-good Appearance
There are over 150 different dog breeds, from tiny Chihuahuas to giant Great Danes, but they are the same species and all are descendants of wolves. A dog with a good-looking may sell a good price.
-increase its nutritional value
-higher-yielding and better food quality
selective breeding modifies teosinte's few fruitcases (left) into modern corn's rows of exposed kernels (right).
There is no corn ten thousands years ago, corn is a product of artificial selection. Corn is evolved from teosinte. But why and how do human do that? A teosinte ear is only 2-3 inches long with five to 12 kernels, Teosinte kernels are also encased in a hard coating. For humans, the tooth-cracking coating was to hard to eat. So, these kinds of characteristics seem as undesirable and have to selectively reduce. Eventually, human have evolved corns from teosinte. A corn has 12 inches ear that boasts 500 or more kernels, and corn is encased by a paper-thin, translucent tissue.
The artificial selection of corn has resulted a hardier, higher-yielding and better appearance corn plants.
More examples of artificial selection…
wild sunflowers (left) and domestic sunflower-result of artificial flowers (right)
milk production in cows (to have higher yielding)
Wild tomatoes (left) and domestic tomatoes (right)
How do process artificial selection?
Is there any disadvantage?
Everything has an opposite side. Some of the disadvantages of artificial selection are, it may cause mutation or produce new problems.
For example, there is a new way of breeding chickens. However, these chickens do not have feathers. The male chickens may not able to mate because they cannot flap their wings. Also, these “feather-free” chickens are more often attacked by mosquito than the normal chickens. They are more often to get sunburn because they do not have feather to protect their skin.In this example, we have produced chickens that satisfy our want, we can make more money; but how about the chicken? They are suffering from their appearance. another example is Plants/animals without these characteristics are less likely to survive as they do not have the fertilizers and pesticides which provide by human.
We have transformed our lifestyle and environment by evolving all the major crops that we depend upon today: corn, rice. It seems a good idea to process artificial selection to provide more food (higher-yielding) and better food quality (better taste and increase of nutritional value). However, there are also some advantages such as more susceptible to disease or mutations.
Reference:
http://evolution.berkeley.edu/evolibrary/news/070201_corn
http://www.nsf.gov/news/news_summ.jsp?cntn_id=104207
http://en.wikipedia.org/wiki/Artificial_selection#Historical_development
