As companies press ahead with their experiments and marketing efforts, a rich public debate must tackle important questions: Is it ethically acceptable to use human genes in animals to produce biopharmaceuticals? Are these biopharmaceuticals safe? What will be the fate of nonproductive GE male offspring, and of GE female animals, when they come to the end of their “useful” lives?
Those ethical questions become more concrete when considering the ecological impacts of animal engineering. Here, the risks to future biodiversity and species survival are significant. Professor William Muir, director of the Purdue University High Definition Genomics Center, likens transgenic organisms to exotic species that can invade new areas, disrupting ecosystems and displacing other species (1). When the gypsy moth was introduced to the East Coast to increase silk production, it did not produce silk but rather quickly proliferated and destroyed plant life across the country. An escaped transgenic organism, Muir says, could pose a similar risk if the new gene was able to adapt and extend its range into different environments. For instance, a freshwater catfish engineered to tolerate salt-water could escape, enter the ocean, and displace established species, posits Muir (2).
According to Muir, escaped transgenic animals, through interbreeding, can introduce a maladapted new gene into wild populations that lowers the net fitness of the animal. Ultimately, inserting this gene could lead to the extinction of both the escaped transgenic population and its wild relatives. In a process Muir calls ”Darwin on his head,” Trojan genes give transgenic animals an initial advantage over their wild counterparts, but, through an ironic twist on natural selection, these genes lower their long-term fitness and threaten to bring the whole species down with them. In the bleak arithmetic of the Trojan gene, according to Muir, if just 60 genetically altered fish were released into a population of 60,000 native fish, there would be complete extinction in forty fish generations (2). This chilling scenario is of urgent concern, not just with GE fish, but with virtually any mobile GE species.
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1 Pew Initiative on Food and Biotechnology, Biotech in the Barnyard: Implications of Genetically Engineered Animals (proceedings of a workshop sponsored by the Pew Initiative on Food and Biotechnology, September 24-25, 2002, Dallas, TX).
2 William M. Muir and Richard D. Howard, “Possible Ecological Risks of Transgenic Organism Release When Transgenes Affect Mating Success: Sexual Selection and the Trojan Gene Hypothesis,” PNAS 96, no. 24 (November 23, 1999): 13853-58.
