how is natural variation used in artificial selection?

Answer 1

If everything was the same, you would never be able to produce a difference by selecting specific parents, would you? It is only when there's variation that you can choose the MOST of something.

Answer 2

Natural variation in artifcial selection, or genetic engineering, is used by selecting favorable naturally occuring various trait(s) in an organism(s) so that offspring(s) of that organism(s) will exhibit those trait(s) deemed desirable. good exaples are the multitude of dog breeds and vast types of fruits and vegetables.