The emergence of primary strategies in evolving virtual-plant populations

A common practice by those searching for generalities in ecological systems has been to form species groups according to similarities in their suites of traits (termed a ‘strategy’). Field and theoretical studies have strongly suggested that resource availability and disturbance frequency have played primary selective roles in the evolution of species traits that has resulted in the existence of a predictable pattern of strategy variation within a resource–disturbance parameter space. We investigated whether this recognizable pattern (of strategy variation) would emerge if model plant populations evolved in environments contrasting in nitrogen availability and disturbance frequency alone. To address this, a mutable single plant model was developed that incorporated 29 mutable parameters controlling plant life history, physiological and morphological traits. Populations of these were ‘grown’ in a spatially explicit model environment that allowed mechanistic competition for light and nitrogen and long-term, multi-generational simulations. The strategies that evolved showed a pattern of variation that strongly conformed to plant strategy theory. Our model provides strong supporting evidence that resource availability and disturbance frequency can act as primary selective forces in plant evolution, resulting in the existence of predictable, environmentally correlated suites of traits. However, several plant traits did not evolve as predicted by field evidence and the reasons for this are discussed.