A Spatially-Explicit Analysis of Crop-to-Crop Gene Flow in Cotton

G flow between crop varieties has attracted increased attention in recent years, due to the potential ecological and economic impacts of gene flow from genetically engineered (GE) crops. Long before GE crops existed, however, growers worked to limit unwanted gene flow, particularly in seed production. Because gene flow between crop fields typically declines as the distance between fields increases, strategies for reducing gene flow often include increasing the distance between fields1. Establishing reasonable separation distances requires knowledge of the factors contributing to gene flow and the relative importance of these factors. Many studies have measured the decline in gene flow from GE crops with incresing distance from individual source fields, but few assessed gene flow patterns at the scale of commercial agricultural landscapes. In an empirical study published in November in PLoS ONE2, we introduced a statistical approach for assessing how gene flow is affected by multiple GE fields in a landscape and by the abundance of pollinating insects. Because commercial agricultural landscapes can be complex, and many factors can simultaneously contribute to gene flow, analyses that simultaneously account for gene flow from multiple GE fields can be more useful than simpler models based solely on distance from a single source field.