A graphical theory of competition on spatial resource gradients

TL;DR

This paper develops a graphical theory to understand how spatial resource gradients influence competition outcomes among species, revealing conditions for coexistence and stable states in one-dimensional habitats.

Contribution

It introduces a novel graphical framework for analyzing competition in spatial environments, highlighting how resource gradients affect species interactions and coexistence.

Findings

Success of invasion depends on resource gradient slopes.

Coexistence in uniform environments can lead to alternative stable states spatially.

Differences in growth, mortality, or dispersal enable coexistence or dominance.

Abstract

Resource competition is a fundamental interaction in natural communities.However little is known about competition in spatial environments where organisms are able to regulate resource distributions. Here, we analyze the competition of two consumers for two resources in a one-dimensional habitat in which the resources are supplied from opposite sides. We show that the success of an invading species crucially depends on the slope of the resource gradients shaped by the resident. Our analysis reveals that parameter combinations which lead to coexistence in a uniform environment may favor alternative stable states in a spatial system, and vice versa. Furthermore, differences in growth rate, mortality or dispersal abilities allow a consumer to coexist stationarily with - or even outcompete - a competitor with lower resource requirements. Applying our theory to a phytoplankton model, we explain shifts in the community structure that are induced by environmental changes.