Natural variation, natural selection, artificial selection, genetic engineering, etc.

Some theorems on artificial selection was created in 1934.

Nature plays no direct role in artificial selection. That is the difference between artificial selection and natural selection.

Nature does play some indirect roles in artificial selection. One indirect role is in providing the organisms with which one beings the artificial selection. Another is in influencing the choices of the organism performing the artificial selection.

Variation in the organisms under selection. In both artificial selection and natural selection there must be heritable variations that have the possibility of being in the case of artificial selection what the selector wants in the organism and in thje case of natural selection survivability and reproductive advantages.

Humans directly affect artificial selection. They do this by selecting the specific traits that they prefer which they cannot don in a natural selection.