Negotiation of mutualism: rhizobia and legumes

Akçay, Erol; Roughgarden, Joan

doi:10.1098/rspb.2006.3689

Cited by 42 publications

(75 citation statements)

References 23 publications

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“…Cooperative game theory proved to be useful in the study of human behaviour, but has rarely been applied to coalitions in non-human animals. This is at least partly because it remains unclear how animals could negotiate without language and how any agreement could be enforced (McNamara et al, 2006;Akcay & Roughgarden, 2007;Binmore, 2010). One notable exception is Noë (1990), who used a veto game from cooperative game theory to explain patterns of coalition formation among adult males in a group of wild baboons.…”

Section: General Theoretical Perspectivesmentioning

confidence: 99%

Coalitions in theory and reality: a review of pertinent variables and processes

Bissonnette

Perry

Barrett

et al. 2015

Behav

104

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Coalitions and alliances are ubiquitous in humans and many other mammals, being part of the fabric of complex social systems. Field biologists and ethologists have accumulated a vast amount of data on coalition and alliance formation, while theoretical biologists have developed modelling approaches. With the accumulation of empirical data and sophisticated theory, we are now potentially able to answer a host of questions about how coalitions emerge and are maintained in a population over time, and how the psychology of this type of cooperation evolved. Progress can only be achieved, however, by effectively bridging the communication gap that currently exists between Coalitions in theory and reality empiricists and theoreticians. In this paper, we aim to do so by asking three questions: (1) What are the primary questions addressed by theoreticians interested in coalition formation, and what are the main building blocks of their models? (2) Do empirical observations support the assumptions of current models, and if not, how can we improve this situation? (3) Has theoretical work led to a better understanding of coalition formation, and what are the most profitable lines of inquiry for the future? Our overarching goal is to promote the integration of theoretical and field biology by motivating empirical scientists to collect data on aspects of coalition formation that are currently poorly quantified and to encourage theoreticians to develop a comprehensive theory of coalition formation that is testable under real-world conditions.

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Section: General Theoretical Perspectivesmentioning

confidence: 99%

Coalitions in theory and reality: a review of pertinent variables and processes

Bissonnette

Perry

Barrett

et al. 2015

Behav

104

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“…We model the negotiation process between a legume host and two nodules, each occupied by a single rhizobial genotype, on the basis of the dynamics introduced by Akçay and Roughgarden (2007). We label the nodules N1 and N2.…”

Section: The Negotiation Model With Two Nodulesmentioning

confidence: 99%

“…A recent model by Akçay and Roughgarden (2007) is useful for answering these questions. In keeping with the trade metaphor, this model considers cooperation as the outcome of biochemical "negotiations" between the plant and the rhizobia.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to the purely plant-controlled sanctions model, the negotiation model affords both partners some degree of control over the outcome and predicts a stable division of benefits to each party. Akçay and Roughgarden (2007) proposed that this kind of negotiation process might underlie differential rewarding of nodules. However, they did not venture beyond the simplest case of a single nodule on one plant and did not model variation in rhizobium traits that would make rhizobia more or less mutualistic.…”

Section: Introductionmentioning

confidence: 99%

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Negotiation, Sanctions, and Context Dependency in the Legume-Rhizobium Mutualism

Akçay

Simms

2011

The American Naturalist

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Two important questions about mutualisms are how the fitness costs and benefits to the mutualist partners are determined and how these mechanisms affect the evolutionary dynamics of the mutualism. We tackle these questions with a model of the legumerhizobium symbiosis that regards the mutualism outcome as a result of biochemical negotiations between the plant and its nodules. We explore the fitness consequences of this mechanism to the plant and rhizobia and obtain four main results. First, negotiations permit the plant to differentially reward more-cooperative rhizobia-a phenomenon termed "plant sanctions"-but only when more-cooperative rhizobia also provide the plant with good outside options during negotiations with other nodules. Second, negotiations may result in seemingly paradoxical cases where the plant is worse off when it has a "choice" between two strains of rhizobia than when infected by either strain alone. Third, even when sanctions are effective, they are by themselves not sufficient to maintain cooperative rhizobia in a population: less cooperative strains always have an advantage at the population level. Finally, partner fidelity feedback, together with genetic correlations between a rhizobium strain's cooperativeness and the outside options it provides, can maintain cooperative rhizobia. Our results show how joint control over the outcome of a mutualism through the proximate mechanism of negotiation can affect the evolutionary dynamics of interspecific cooperation. Disciplines Biology | Developmental Biology | Evolution CommentsAt the time of publication, author Erol Akçay was affiliated with the University of Tennessee. Currently, he is a faculty member at the Department of Biology at the University of Pennsylvania. Online enhancements: appendix, Mathematica file.abstract: Two important questions about mutualisms are how the fitness costs and benefits to the mutualist partners are determined and how these mechanisms affect the evolutionary dynamics of the mutualism. We tackle these questions with a model of the legumerhizobium symbiosis that regards the mutualism outcome as a result of biochemical negotiations between the plant and its nodules. We explore the fitness consequences of this mechanism to the plant and rhizobia and obtain four main results. First, negotiations permit the plant to differentially reward more-cooperative rhizobia-a phenomenon termed "plant sanctions"-but only when more-cooperative rhizobia also provide the plant with good outside options during negotiations with other nodules. Second, negotiations may result in seemingly paradoxical cases where the plant is worse off when it has a "choice" between two strains of rhizobia than when infected by either strain alone. Third, even when sanctions are effective, they are by themselves not sufficient to maintain cooperative rhizobia in a population: less cooperative strains always have an advantage at the population level. Finally, partner fidelity feedback, together with genetic correlations between a rhizobium strain...

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“…For rhizobia, trade-offs exist between fixing nitrogen for the benefit of the plant versus hoarding resources like polyhydroxybutyrate (Hahn & Studer 1986;Cevallos et al 1996;Denison & Kiers 2004a,b;Akçay & Roughgarden 2007), which can enhance future survival or reproduction (Cai et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Human selection and the relaxation of legume defences against ineffective rhizobia

2007

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Enforcement mechanisms are thought to be important in maintaining mutualistic cooperation between species. A clear example of an enforcement mechanism is how legumes impose sanctions on rhizobial symbionts that fail to provide sufficient fixed N 2 . However, with domestication and breeding in high-soil-N environments, humans may have altered these natural legume defences and reduced the agricultural benefits of the symbiosis. Using six genotypes of soya beans, representing 60 years of breeding, we show that, as a group, older cultivars were better able to maintain fitness than newer cultivars (seed production) when infected with a mixture of effective and ineffective rhizobial strains. Additionally, we found small differences among cultivars in the ratio of effective : ineffective rhizobia released from their nodules, an indicator of future rhizobial strain fitness. When infected by symbionts varying in quality, legume defences against poor-quality partners have apparently worsened under decades of artificial selection.

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Negotiation of mutualism: rhizobia and legumes

Cited by 42 publications

References 23 publications

Coalitions in theory and reality: a review of pertinent variables and processes

Coalitions in theory and reality: a review of pertinent variables and processes

Negotiation, Sanctions, and Context Dependency in the Legume-Rhizobium Mutualism

Human selection and the relaxation of legume defences against ineffective rhizobia

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