Resource heterogeneity and the evolution of public goods cooperation.

Peter Stilwell,Angus Buckling,Chris Lowe,Siobhan O'Brien,Elze Hesse,Andy Gardner

doi:10.1002/evl3.158

Abstract

Heterogeneity in resources is a ubiquitous feature of natural landscapes affecting many aspects of biology. However, the effect of environmental heterogeneity on the evolution of cooperation has been less well studied. Here, using a mixture of theory and experiments measuring siderophore production by the bacterium Pseudomonas aeruginosa as a model for public goods based cooperation, we explore the effect of heterogeneity in resource availability. We show that cooperation in metapopulations that were spatially heterogeneous in terms of resources can be maintained at a higher level than in homogeneous metapopulations of the same average resource value. The results can be explained by a positive covariance between fitness of cooperators, population size, and local resource availability, which allowed cooperators to have a disproportionate advantage within the heterogeneous metapopulations. These results suggest that natural environmental variation may help to maintain cooperation.

Highlights

Heterogeneity in resource availability is a ubiquitous feature of natural landscapes that has been shown to influence population dynamics and community structure
We investigated the effect of spatial heterogeneity in resource availability—while maintaining the same mean level of resources—on the evolution of cooperation
We first developed an analytical model showing that under hard selection, where fitness is determined relative to all members within the metapopulation, resource heterogeneity can promote higher levels of cooperation

Summary

Introduction

Heterogeneity in resource availability is a ubiquitous feature of natural landscapes that has been shown to influence population dynamics and community structure. Resource availability has been shown to affect the cost of cooperation but will affect population size. We first develop an analytical model formalizing our hypothesis and conduct experiments to investigate the role of resource heterogeneity on pyoverdine production in the bacterium Pseudomonas aeruginosa. The contribution of populations to future generations is unlinked from their current productivities, and so resource heterogeneity has no impact on the level of cooperation. In a series of in vitro experiments, we first confirm that resource levels have an effect on P. aeruginosa cooperator fitness in the short term, before conducting a longer term evolution experiment that supports the prediction that heterogeneous environments support higher levels of cooperation than homogeneous environments. Evolution Letters published by Wiley Periodicals, Inc. on behalf of Society for the Study of Evolution (SSE)

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Conclusion