Starting in the 1990s, a number of important insights about species coexistence were derived largely working from Lotka and Volterra’s classic models of population interaction, or from MacAurthur’s seminal models of consumer-resource dynamics. These important insights have become known as Modern Coexistence Theory (MCT), or sometimes as contemporary niche theory; even though they largely rely on models from the 1920s through to the 1960s. In many ways this renaissance was a direct response to neutral theory. Because coexistence is a population level process, recent work has begun to focus on gardens of annual plants and rely on simple annual plant demographic models to allow for experimental tests of theories. Annual plants are ideal for this because it is straightforward to capture demographic consequences in annually reproducing plants. Here, I extend these population models to include trait interactions, and even trait evolution by developing them into an evolutionary game. Using the G-function approach, I am able to include multi-dimensional functional traits, plant-plant interactions mediated directly through trait values, and population dynamics in one simple model. This is achieved by treating competition coefficients as functions of trait values, rather than as constants.
Results/Conclusions
One of the limitations of many trait based models of coexistence is that one must know the trait distribution of a community a priori and then put that into the model. This is slightly unsatisfying because in many ways it seeks a description of a community by already starting from a fairly complete description of a community. The advantage of the evolutionary game theory approach is that one need not know the trait distribution of a community a priori. Instead, the trait distribution, and the species diversity of a community both emerge as sets of evolutionarily stable strategies (ESS). The model reveals how the interplay between stabilising selection and disruptive selection may both constrain the traits of a community, and the diversity of a community. When ecological processes promote disruptive selection both species and trait diversity increase, and when ecological processes promote stabilising selection the opposite occurs. Evolutionary game theory is a powerful framework for linking ecological and evolutionary processes, and I believe can take us several steps further towards a theory of coexistence that is predictive.