Coexistence in an inhomogeneous environment

TL;DR

This paper explores how spatial inhomogeneity and geometry influence species competition and coexistence in two-dimensional environments, revealing a new coexistence phenomenon absent in simpler models.

Contribution

It extends the Kessler-Sander model to two dimensions, demonstrating a novel coexistence regime influenced by environmental geometry.

Findings

Coexistence occurs at intermediate densities in 2D models.

High and low densities lead to species extinction.

Geometry significantly affects dispersal and competition outcomes.

Abstract

We examine the two-dimensional extension of the model of Kessler and Sander of competition between two species identical except for dispersion rates. In this class of models, the spatial inhomogeneity of reproduction rates gives rise to an implicit cost of dispersal, due to the tendency to leave favorable locations. Then, as in the Hamilton-May model with its explicit dispersal cost, the tradeoff between dispersal case and the beneficial role of dispersal in limiting fluctuations, leads to an advantage of one dispersal rate over another, and the eventual extinction of the disadvantaged species. In two dimensions we find that while the competition leads to the elimination of one species at high and low population density, at intermediate densities the two species can coexist essentially indefinitely. This is a new phenomenon not present in either the one-dimensional form of the Kessler-Sander model nor in the totally connected Hamilton-May model, and points to the importance of geometry in the question of dispersal.