The impact of initial evenness on biodiversity maintenance for a four-species in silico bacterial community

•We model a four species bacterial community with fully connected competition.•The model allows initial community evenness to be varied, unlike previous studies.•Simulation outcomes depend strongly on initial evenness and competition scheme.•The system is generally unstable; extinction events are frequent.•Initial evenness has a small stabilizing effect on system dynamics.

Initial community evenness has been shown to be a key factor in preserving the functional stability of an ecosystem, but has not been accounted for in previous modelling studies. We formulate a model that allows the initial evenness of the community to be varied in order to investigate the consequent impact on system diversity. We consider a community of four interacting bacterial species, and present a stochastic, spatial individual-based model simulating the ecosystem dynamics. Interactions take place on a two-dimensional lattice. The model incorporates three processes: reproduction, competition and mobility. In addition to variable initial evenness, multiple competition schemes are implemented, modelling various possible communities, which results in diverse coexistence and extinction scenarios. Simulations show that long-term system behaviour is strongly dependent on initial evenness and competition structure. The system is generally unstable; higher initial evenness has a small stabilizing effect on ecosystem dynamics by extending the time until the first extinction.