Exploitation of environmental heterogeneity by spatial division of labour in a clonal plant

1. The economic principle of spatial division of labour comprises two basic features, specialization in the performance of specific tasks and close co-operation by potentially independent, spatially separated subunits of a higher-level organizational system. Space-economic theory predicts large benefits from such a spatial division of labour if essential resources are heterogeneously distributed and if high-availability zones for these resources do not spatially coincide. In this paper, evidence is provided that a spatial division of labour may also occur in clonal plants growing in spatially heterogeneous environments. 2. Clonal fragments of the stoloniferous herb Trifolium repens L., consisting of two interconnected groups of ramets, were exposed to contrasting levels of light and water supply. Ramet groups specialized morphologically in the uptake of the locally most abundant resource and they exchanged both water and assimilates. This division of labour significantly increased the performance of the entire plant in terms of fitness-related traits such as biomass and clonal offspring production. 3. It is concluded that spatial division of labour may contribute to the apparent success of clonal plant species in many natural habitats by enabling them to efficiently exploit environmental patchiness. The implications of these results for the understanding of foraging strategies of clonal plants and the general notion of habitat heterogeneity in plant ecology are discussed.