Darwinism  is defined as an existence of variations-differences among members of the same species-and that these variations that prove helpful to a plant or an animal in  its struggle for existence better enable it to survive and reproduce. These favorable variations are thus transmitted to the offspring of the survivors.  This is called natural selection.(2) (4)

In Relation to Genetically Modified Foods:

       Since the ecosystem has been improving itself for thousands of years through genetic mutations, genetic engineering is altering what has been modified through evolution.  Genetically engineering the crops involves transferring of genes that does not naturally occur and therefore is upsetting the balance of nature that has been established.  Changing the genes of a seed leads to a change in the life of the organisms that feed from or live near the crop.  An organism that may have otherwise survived natural selections will then not survive because of a change that humans imposed on the environment.

 
Definition from: www.dictionary.com