Stable trimorphic coexistence in a lattice model of spatial competition with two site types

TL;DR

This paper demonstrates that stable coexistence of habitat specialists and a generalist can occur in a spatial lattice model with heterogeneity, even when such coexistence is impossible in a mean field approximation, highlighting the importance of spatial structure.

Contribution

It introduces a simple lattice model showing stable coexistence of multiple species due to spatial heterogeneity, contrasting with mean field predictions.

Findings

Stable coexistence observed in the lattice model.

Mean field approximation predicts no coexistence.

Spatial structure enables coexistence beyond mean field predictions.

Abstract

I examine the effect of exogenous spatial heterogeneity on the coexistence of competing species using a simple model of non-hierarchical competition for site occupancy on a lattice. The sites on the lattice are divided into two types representing two different habitats or spatial resources. The model features no temporal variability, hierarchical competition, type-dependent interactions or other features traditionally known to support more competing species than there are resources. Nonetheless, stable coexistence of two habitat specialists and a generalist is observed in this model for a range of parameter values. In the spatially implicit mean field approximation of the model, such coexistence is shown to be impossible, demonstrating that it indeed arises from the explicit spatial structure.