Genetic engineering is the branch of biotechnology in which the genome of organisms is modified for industrial, medical, environmental and other purposes. An example of genetic engineering is transgenic organisms in which sequences or genes from other species are inserted, as in the case of pest-resistant corn. This modified corn has a gene from the bacterium Bacillus thuringiensis, this gene makes the corn produce a toxin that is harmful to pests. Environmentally, this corn has an advantage over other wild species and because of this, if not properly controlled, could displace other corn species as it would be the only survivor of pests, which in turn would decrease the genetic variability of corn plants in the ecosystem.