The Impact of Obstruction on a Model of Competitive Exclusion in Plants

This study extends an earlier work on an agent based model of competitive exclusion in plants by adding obstructions to a toroidal agent world. The agents are called grid plants, whose genome specifies their pattern of growth and when they make seeds. Seed production is the figure of merit used to assess the success of grid plants. Barriers are found to substantially inhibit seed production, out of proportion to the amount of space they occupy. Two types of barriers are used, ones that occupy productive space in the simulation and ones that block growth between grids of the simulation but occupy no space. Both sorts of barriers are found to inhibit seed production well in excess of the physical space obstructed, nor is fraction of obstruction a strong determinant of the level of inhibition. There is a cooperative effect from both seed mortality and barriers: past some threshold dependent on both, the plants take much longer to achieve exponential growth, if at all. A very strong effect of nonlocal adaptation is apparent in the results, where plants evolved under increasing hardship are initially better adapted, even to other boards, but the effect reverses when evolutionary pressure becomes too high.