GMO and Environment: Once a Gene’s In, Where Does It Go?


What is gene flow?

•Gene flow is a phenomenon that is constantly occurring within our environment.  Cross-pollination, and possibly many other unknown processes, integrate segments of DNA from one organism into the genome of another organism.  This can occur between  organisms of the same species or between organisms of different species.


Gene flow and GMO

•Although gene flow is a naturally occurring process, some fear that the transfer of the genes of GMO might cause environmental problems.  Many of the GMO used widely in agriculture have been engineered with novel genes for attributes such as herbicide resistance and insect resistance.


•Genetic modifications often give the GM crop a competitive advantage.  If a GM crop “escapes” from its field it has the potential to replace its non-GM counterpart.  This is especially a problem when many related non-GM species are native to the area the crop is planted in.  When the genes from the GM crop leave the field in which they were planted there are plants that fill a similar niche with which they will compete, and because the GM crop has the advantage, they may take over.


•On the other hand,  environmental benefits of such modification include protection against insect damage, herbicide tolerance for innovative farming, reduction in the amount of land needed for agriculture, conservation of resources through use of less labor, fuel, fertilizer and water, water quality protection, and protection against plant diseases


Although GMO are engineered to possess genes not normally found in that organism, the DNA incorporated into the genomes of GMO is taken from other living organisms that possess a desirable trait. Therefore, the genes incorporated into the genome of engineered organisms are already in the process of gene transfer from their original hosts to countless other organisms in the environment.




How do GMO affect biodiversity?

•There is no simple answer.  It depends on the crop, the modification, the environment the crop is planted in, and the way people respond to it.  First, let’s define biodiversity.  There are two components of biodiversity.  The first is the number of different species in an area, or the species richness; the other is a measure of the diversity within a species, or genetic diversity. 


•A monoculture is a field planted with genetically similar individuals.  Traditional agriculture makes use of monocultures by replacing a field that had many species with a field containing only one: just rice, just corn, etc.  GM crops take this one step farther.  Not only is the field planted with only one species, but all the individuals within the species are genetically identical because they all came from one genetically modified source plant.


•Aside from the fact that monocultures inherently contain very little genetic diversity, they also make the crop species vulnerable to invasion by insects, fungus, etc.


Further information

Gene flow article, link to page from which you can download PDF:


Maize article, DNA invasion?:


When GMO fish move into the non-GMO population:


Monoculture, importance of diversity article:


Have Genes, Will Travel: Issues Raised by Gene Flow from Genetically Engineered Crops