Exploration and exploitation of resource patches by clonal growth: a spatial model on the effect of transport between modules

Modular development in plants facilitates to cope with environmental heterogeneity. Differential natality and mortality of the modules in resource-rich versus poor sites can lead to selective occupancy of favorable habitat patches (foraging for good sites). In some species, especially in clonal plants, the modules are quite autonomous, and perceive and respond to local habitat conditions individually (splitter strategy). In others, the modules are physiologically integrated, and exchange water, nutrients and assimilates. In the simplest case, the resource moves from rich to poor sites, thus, the contrast between habitat patches is evened out within the plant (integrator strategy). Integration can significantly rearrange the pattern of resources that are available to the modules. We studied the effect of integration on the efficiency of foraging. lied a spatially explicit (cellular automata) model, in which we varied the size and proportion of resource-rich patches in the habitat. In each simulation, a splitter and an integrator species were competing for this patchy resource. We compared the dynamics of module populations. We studied the spatial association between the splitter, the integrator, and the resource by an information statistical method of pattern analysis. Thus, we gained a quantitative description of habitat structure, and a related measure for the efficiency of foraging. nd that splitting always promoted foraging, but at the expense of slower population growth. This became critical when the distribution of resource patches was sparse. In these cases, the characteristically fugitive spatial behavior of the integrator facilitated its quick spreading into the gaps that has been left vacant by the splitter. Better tolerance of the integrator to resource scarcity, and better chance for colonizing distant patches enabled its long-term persistence, occasionally even dominance over the area. Therefore, the adaptive advantage of splitting versus integration depended sensitively on the spatial pattern of resource patches.