Transgene Escape Monitoring, Population Genetics, and the Law

T crop species have been adopted by a growing number of countries in the past decade, and the acreage devoted to transgenic species has expanded considerably (James 2005). In the United States alone, the National Agricultural Statistics Service of the US Department of Agriculture (USDA) reported that corn acreage planted with transgenic hybrids expanded from 26 percent of the crop in 2001 to 52 percent in 2005. Furthermore, transgenics now account for the majority of the US canola, cotton, papaya, and soybean crops. Given the continuing pace of advances in plant biotechnology, transgenic agriculture is likely to continue to grow in popularity in years to come. Much has been written about both the advantages associated with the culture and consumption of transgenic plants and the ecological and agricultural problems that might accompany unintended hybridization of transgenic plants with wild relatives (e.g., Royal Society et al. 2000, Pilson and Prendeville 2004, Snow et al. 2005). As for potential problems, it has been postulated that the migration of transgenes coding for herbicide or pest resistance into native or naturalized weedy populations of plants may result in the evolution of weeds that are more difficult to control (Kareiva et al. 1994, Ellstrand 2003a, Snow et al. 2005); that migration of maladaptive transgenes into populations of wild species may reduce their fitness and lead to local population decline (Muir and Howard 1999, Hedrick 2001, Wolf et al. 2001, Ellstrand 2003a, Haygood et al. 2003); and that transgenic plants and their hybrids may be harmful to nontarget consumer organisms, such as native plant-feeding insects and their predators (Losey et al. 1999, Sears et al. 2001, Zangerl et al. 2001, Groot and Dicke 2002). In the past few years, reports of transgene migration from agricultural to wild populations have begun to emerge. For example, transgenic canola (Brassica napus) in Quebec has been reported to hybridize with weedy Brassica rapa (Warwick et al. 2003); and more recently, in Oregon, transgene escape has been reported from field trials of creeping bentgrass (Agrostis stolonifera) into natural populations of three compatible Agrostis species (Watrud et al. 2004, Reichman et al. 2006). Such reports highlight the potential necessity of developing monitoring methods to determine whether and why a particular transgene may change in frequency once it