Abstract
For some plant species, intraspecific belowground competition takes a form of the tragedy of the commons (TOC), where competing neighbours invest more in root systems than would be appropriate for optimal nutrient uptake for the group. However, there are also species not involved in TOC, optimizing their root investment according to the ideal free distribution (IFD).
Important and yet unresolved question is which ecological and evolutionary forces determine whether a species follows the strategy yielding TOC or IFD. We combine existing mathematical models of TOC and IFD rooting strategies in a matrix model, allowing us to compare the strategies in different ecological contexts, and we test the model predictions via meta-analysis of published competition experiments.
TOC strategy is evolutionary stable in almost all ecological conditions. Extrapolated to macroevolutionary scale, this means that once TOC strategy appears in an evolutionary lineage, it is unlikely to disappear.
Our meta-analysis suggests that TOC strategy is indeed phylogenetically clustered within Fabaceae or the rosids clade. We show that evolutionary history, in addition to current ecological conditions, should be responsible for plant belowground competition strategy within species.
Evolutionary history thus provides a new perspective on root competition strategies and should be considered in its investigation.