On strategies of plant behaviour: Evolutionary games of habitat selection, defence, and foraging

Background: Strategies of habitat selection, defence, and foraging depend critically on population density and the frequency of alternative strategies: they are evolutionary games. Although commonly modelled in studies of animal behaviour, they are less frequently used to provide insights into the behaviour of plants. A 'review' and analysis of how these universal strategies apply to plants should help motivate further development of plant evolutionary games. Questions: Should plants practise density-dependent habitat selection? Do games of plant defence depend on demography and habitat quality? How similar are games of competition for nutrients and light? Methods and models: Assessments of eco-evolutionary dynamics with computer simulations (habitat selection), evolutionary invasion analysis (defence), and G-functions (foraging). Results: Selection gradients for pre-emptive habitat selection are steeper than those for passive dispersal and yield an advantage that increases with population density. The evolutionarily stable defence level in a homogeneous environment is proportional to the ratio of survival by mature versus immature plants. In heterogeneous environments, investments in herbivore defence depend on habitat quality and are resolved by habitat selection. Games of competition for both nutrients and light predict Tragedies of the Commons in which size, density, and investment in tissue that does not directly contribute to fitness depend on the source of competition. Conclusion: Much of the dynamic feedback between the ecology of plants and their evolution can be understood with models of three universal processes: habitat selection, safety and defence against enemies, and foraging for nutrients and other resources. The specifics of models may differ among taxa, but not the underlying density and frequency dependence of their eco-evolutionary strategies.