Another issue is the impact of these interactions on pathogen and plant fitness, which are important to appreciate before drawing evolutionary models. Although B. cinerea can indeed be a destructive pathogen in agricultural systems it is unclear to this reviewer how it impacts the fitness of its native host plants; and vice versa the extent to which this pathogen relies on plant infection for its reproduction (unlike say an obligate biotroph). To me this is a critical part of the comparison between B. cinerea and other pathogens/parasites that have unequivocal negative impact on their hosts and/or are dependent on their hosts leading to strong selection dynamics for resistance/virulence. In other words, strong selection pressures are an important aspect of the equation when weighing theoretical expectations for an arms race.