title: Restricting mutualistic partners to enforce trade reliance.
abstract: Mutualisms are cooperative interactions between members of different species, often involving the trade of resources. Here, we suggest that otherwise-cooperative mutualists might be able to gain a benefit from actively restricting their partners' ability to obtain resources directly, hampering the ability of the restricted partner to survive and/or reproduce without the help of the restricting mutualist. We show that (i) restriction can be favoured when it makes the resources of the restricting individual more valuable to their partner, and thus allows them to receive more favourable terms of trade; (ii) restriction maintains cooperation in conditions where cooperative behaviour would otherwise collapse; and (iii) restriction can lead to either an increase or decrease in a restricted individual's fitness. We discuss the applicability of this scenario to mutualisms such as those between plants and mycorrhizal fungi. These results identify a novel conflict in mutualisms as well as several public goods dilemmas, but also demonstrate how conflict can help maintain cooperation.
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: Gregory A K
authors.initials: GA
authors.lastname: Wyatt
authors.affiliation: Institute of Ecological Sciences, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
authors.forename: E Toby
authors.initials: ET
authors.lastname: Kiers
authors.affiliation: School of Biology, University of St Andrews, Dyers Brae, St Andrews KY16 9TH, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Gardner
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.|Magdalen College, Oxford OX1 4AU, UK.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: West
mesh_terms: D005658:Fungi / Q000502:physiology*; D008954:Models, Biological; D038821:Mycorrhizae / Q000502:physiology*; D018521:Plant Physiological Phenomena; D010944:Plants / Q000382:microbiology*; D013559:Symbiosis
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