Evolution of nutrient acquisition: when space matters

Abstract

Summary Evolution of nutrient acquisition by plants should depend on two forces: local competition is based on the capacity to exploit the local nutrient resource, and regional competition is based on the capacity to occupy the whole landscape through seed production and dispersal. We build a spatially explicit simulation model where a limiting nutrient is recycled in each local patch of a lattice by individual plants. The model includes both local and regional competition. Heterogeneity in nutrient availability and dispersal limitation mitigate the effect of competition for the local nutrient resource and allow the evolution of lower rates of nutrient uptake. Our spatially explicit model suggests that evolution in richer ecosystems selects ‘expensive’ strategies (high acquisition, low conservation of resources) compared to poor ecosystems. Low rates of nutrient acquisition can be considered as a form of altruism because they leave more resource available for other individuals. Our model thus suggests that the influence of spatial processes on the evolution of altruism is pervasive and is linked to key aspects of ecosystem functioning. Because our model includes both regional and local competition, evolution does not minimize the availability of mineral nutrient, although evolution or species replacement is often thought to minimize the availability of nutrient. Taken together, our work confirms that the interplay between local and regional competition is critical for the evolution of plant nutrient strategies and its effect on ecosystem properties.