Natural selection is the process by which all species evolve to adapt to changing conditions in their environment. Over many generations, desirable traits are built upon by the reproduction of natural hybrids which have proven their ability to withstand new or changed environmental conditions simply by the fact that they have survived those changes and prospered. To put it another way, natural selection is evolution, governed by nature’s “survival of the fittest” law.
Hybridization occurs constantly in nature within closely related family groups. A few of the resulting offspring acquire the qualities needed to thrive in the environment they find themselves in, but many do not. Those that do survive produce their own offspring carrying the same strong survival genes. Descendants of these strong survivors go on to become the parents of the next generation of hybrids. Weaker offspring die out as environmental conditions and stronger hybrids overpower and outnumber them. This delicate balance ensures that the overall survival mechanism of the global food chain, from tiniest micro-organism right through to the largest mammal, stays in tact.
Every species on Earth has evolved, and would continue to evolve, through natural selection if left to their own devices, except for one; man. Man has taken species selection into his own hands and created all manner of closely (and not so closely) related hybrids. Some of these may have eventually occurred in nature, while others most certainly would not.
The practice of artificial selection removes the “survival of the fittest” law from the evolutionary process. Now, we can create hybrids to satisfy our own desires rather than satisfying the need to be strong enough to survive on their own. We can artificially breed animal or vegetable varieties that are unlikely to survive if left to fend for themselves, then artificially nurture and reproduce them. Where naturally selected species and hybrids grow and thrive with no human intervention, artificially selected varieties often require more intensive care to ensure they perform as they are expected to.
Selective breeding of plants and animals for the purpose of perpetuating one or more desirable traits has been carried out by man all through history. Many of the hybrids created in this way would have come about eventually in nature, with varying degrees of success, i.e. survival rates. For this reason their interaction with other life forms is not overly problematic in the scheme of evolution. These artificially selected hybrids still carry the genes of their direct descendants and so the survival of the fittest law still applies. When they are released or escape into a self regulating environment, nature ensures that long term balance prevails and the food chain continues to evolve at its own pace.
Genetic modification, on the other hand, takes artificial selection to an entirely new level. Genetic engineers have mastered the techniques of transferring genes between completely unrelated species to create hybrids never before seen on Earth. Pairings such as these cannot occur in nature due to an inherent species barrier which does not allow cross breeding. For instance, a tomato plant can’t cross breed with a member of the cabbage family and certainly could never cross breed with bacteria or starfish. Genetic engineering has stepped across the species barrier to allow these types of highly controversial artificial selections to occur.
Corn, rice, soy, alfalfa, eggplant, cotton, Eucalyptus and numerous plant types are now carrying alien genes from soil bacteria and other sources to give them resistance to strong chemical herbicides or to render them living pesticides, killing the insects which feed on them. Geneticists have even experimented with transferring a gene from Winter Flounder which live in subzero temperatures to a strawberry plant, giving it the ability to withstand frost. Methods of transferring genes include the use of E.coli and various virus strains to ensure the gene expresses correctly throughout the plant. The list of gene manipulations in the works is vast with many far removed species now joined at their deepest level, their DNA, the basic building block of life itself.
The long term consequences of allowing genetically modified organisms (GMOs) to interact with other life forms, not to mention with each other, are entirely unknown. Some may prove to be too weak to survive the evolutionary process but others could well begin to cause undesirable mutations along the whole global food chain. What does this mean for us humans who sit comfortably on top of that chain? That is a question nobody will know the answer to until the effects start to reveal themselves.
There is much food for thought here…