There Is More to Fitness Than Fecundity: Invasiveness of GM Crops.

Evaluation of fitness of genetically modified crops and their hybrid offspring is critical with the potential introduction of multiple stress tolerance and yield traits. Most academic research has focused on a single vital rate, fecundity, however fitness is also influenced by survival at any stage of the lifecycle and genetic changes that impact that survival may significantly alter plant fitness. Vital rates of open- pollinated and hybrid canola (Brassica napus) were quantified in 5 Canadian locations over 3 years, in three disturbance regimes and two planting densities. Prospective analysis was used to identify vital rates to which the population growth rate (λ) was most sensitive. Retrospective analysis using life table response experiments was used to identify the changes in vital rates that caused changes in l in response to different treatments. Fecundity of hybrid canola was higher but overwintering survival lower than open-pollinated canola, resulting in a similar λ. While all treatments influence λ, disturbance regime had the largest impact. Both biotypes exhibited λ>1 in agricultural sites, but populations were ephemeral in ruderal and natural environments (λ<1). Demographic analysis is an appropriate tool for quantification of fitness and identification of potential invasiveness. λ