Coexistence coalitions in propagule disperser quasi-communities

Many natural ecosystems harbor large numbers of coexisting species competing for far fewer distinct resources, in apparent defiance of the competitive exclusion principle. Various mechanisms have been proposed to explain this apparent paradox, among the most prominent being competition--colonization trade-offs, environmental heterogeneity, and ecological neutrality. We develop a unified stochastic model class that combines all three coexistence narratives in the context of propagule disperser communities and show that this setting encompasses several important classical models. We then prove a general theorem on coexistence at macroscopic equilibria and provide an algorithm that determines equilibrium coalitions solely from readily available matrix spectra, thereby bypassing the costly computation of exact equilibrium states. Using illustrative examples, we demonstrate the potential of this approach for quantifying the relative merits of different coexistence narratives and for studying their synergistic effects.