The Importance of Spatial Heterogeneity and Self-Restraint on Mutualism Stability

The importance of spatial heterogeneity and self-restraint on mutualism stability- a quantitative review

Running title: Quantitative reviewofmutualism maintenance

This is an article

Rui-Wu Wang1, 2 *, Derek W. Dunn 2,Jun Luo 1, Jun-Zhou He 2,3and Lei Shi 3*

1.Center for Ecological and Environmental Sciences, Northwestern Polytechnical University, Xi’an, 710072, China.

2Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan, 650223, China.email: ;

3Statistics and Mathematics College, Yunnan University of Finance and Economics, Kunming, Yunnan, 650221, China.

Appendix

Table A1:Summary information of the studies used for the meta-analysis

In inter-specific mutualisms, cheats are individuals within a population (usually symbionts) that benefit from the cooperative actions of other symbionts and the host, but in return provide the host no or reduced benefits1. Cheats thus incur no or reduced costs of cooperation, whilst still receiving benefits associated with host resource exploitation1. If host resources become fully exploited, cooperative symbionts will thus subsequently receive no benefits even though they incur costs of cooperation2-4.

Any spatial heterogeneityof hosts or host resources maynot be able to solely stabilisea mutualism.Spatial heterogeneitymay often evolve but can ultimately fail to result in the evolutionof cooperation, because a mutant able to overcomespatial heterogeneity barriers to exploit the other mutualist will have higher short-term fitness thancooperative conspecifics in a limited local space5.In some mutualisms, it has been shownempirically that spatial heterogeneity or self restraint may be unable to solely maintain system stability (e.g., in the fig tree-fig wasp mutualism6-8, such asthe mutualism between the moth Greya politellaand its host plant Lithophragma parviflorum9.

References

1Ghoul, M., Griffin, A. S. & West, S. A. Toward an evolutionary definition of cheating. Evolution68, 318-331 (2014)

2Doebeli, M. & Knowlton, N. The evolution of interspecific mutualisms.Proc. Nati. Acad. Sci. USA95, 8676-8680 (1998).

3Boyd, R. & Lorberbaum, J. P. No Pure Strategy Is Evolutionarily Stable in the Repeated Prisoners-Dilemma Game. Nature327, 58-59 (1987).

4Wang, R. W. & Shi, L. The evolution of cooperation in asymmetric systems. Sci. China Life Sci.53, 139-149 (2010).

5Hauert, C. & Doebeli, M. Spatial structure often inhibits the evolution of cooperation in the snowdrift game. Nature428, 643-646 (2004).

6Dunn, D. W. et al. A Role for Parasites in Stabilising the Fig-Pollinator Mutualism. PloS Biol.6, e59 (2008).

7Wang, R. W., Shi, L., Ai, S. M. & Zheng, Q. Trade-off between reciprocal mutualists: local resource availability-oriented interaction in fig/fig wasp mutualism. J. Anim. Ecol.77, 616-623 (2008).

8Wang, R. W., Sun, B. F. & Zheng, Q. Diffusive coevolution and mutualism maintenance mechanisms in a fig-fig wasp system. Ecology91, 1308-1316 (2010).

9Thompson, J. N. & Fernandez, C. C. Temporal dynamics of antagonism and mutualism in a geographically variable plant-insect interaction. Ecology87, 103-112 (2006).

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