Evidence for emergent behaviour in the community-scale dynamics of a fungal microcosm

A stochastic cellular automaton for modelling the dynamics of a two–species fungal microcosm is presented. The state of each cell in the automaton depends on the state of a predefined neighbourhood via a set of conditional probabilities derived from experiments conducted on pairwise combinations of species. The model is tested by detailed comparison with larger–scale experimental microcosms. By employing different hypotheses which relate the pairwise data to the conditional probabilities in the model, the nature of the local and non–local interactions in the community is explored. The hypothesis that the large–scale dynamics are a consequence of independent interactions between species in a local neighbourhood can be excluded at the 5percnt; significance level. The form of the interdependencies is determined and it is shown that the outcome of the interactions at the local neighbourhood–scale depends on the community–scale patterning of individuals. The dynamics of the microcosm are therefore an emergent property of the system of interacting mycelia that cannot be deduced from a study of the components in isolation.