Department of Integrative Biology, 3060 Valley Life Sciences Building #3140, University of California, Berkeley, California 94720-3140 and Plant Conservation Research Center, University of California Botanical Garden, 200 Centennial Drive #5045, Berkeley, California 94720-5045.
Integr Comp Biol. 2002 Apr;42(2):369-80. doi: 10.1093/icb/42.2.369.
Mutualistic interactions are widespread and obligatory for many organisms, yet their evolutionary persistence in the face of cheating is theoretically puzzling. Nutrient-acquisition symbioses between plants and soil microbes are critically important to plant evolution and ecosystem function, yet we know almost nothing about the evolutionary dynamics and mechanisms of persistence of these ancient mutualisms. Partner-choice and partner-fidelity are mechanisms for dealing with cheaters, and can theoretically allow mutualisms to persist despite cheaters.Many models of cooperative behavior assume pairwise interactions, while most plant-microbe nutrient-acquisition symbioses involve a single plant interacting with numerous microbes. Market models, in contrast, are well suited to mutualisms in which single plants attempt to conduct mutually beneficial resource exchange with multiple individuals. Market models assume that one partner chooses to trade with a subset of individuals selected from a market of potential partners. Hence, determining whether partner-choice occurs in plant-microbe mutualisms is critical to understanding the evolutionary persistence and dynamics of these symbioses. The nitrogen-fixation/carbon-fixation mutualism between leguminous plants and rhizobial bacteria is widespread, ancient, and important for ecosystem function and human nutrition. It also involves single plants interacting simultaneously with several to many bacterial partners, including ineffective ("cheating") strains. We review the existing literature and find that this mutualism displays several elements of partner-choice, and may match the requirements of the market paradigm. We conclude by identifying profitable questions for future research.
互利共生关系广泛存在，对许多生物来说是必不可少的，但从理论上讲，它们在面对欺骗行为时能够持续存在是令人费解的。植物与土壤微生物之间的营养获取共生关系对植物进化和生态系统功能至关重要，但我们对这些古老的互利共生关系的进化动态和持续机制几乎一无所知。伙伴选择和伙伴忠诚是应对欺骗者的机制，从理论上讲，它们可以允许互利共生关系在存在欺骗者的情况下持续存在。许多合作行为模型假设存在成对的相互作用，而大多数植物-微生物营养获取共生关系涉及单个植物与众多微生物相互作用。相比之下，市场模型非常适合于单个植物试图与多个个体进行互利资源交换的互利共生关系。市场模型假设一个伙伴选择与从潜在伙伴市场中选择的一组个体进行交易。因此，确定伙伴选择是否发生在植物-微生物互利共生关系中对于理解这些共生关系的进化持久性和动态至关重要。豆科植物与根瘤菌之间的固氮/固碳共生关系广泛存在，历史悠久，对生态系统功能和人类营养至关重要。它还涉及单个植物同时与几个到多个细菌伙伴相互作用，包括无效（“欺骗”）菌株。我们回顾了现有文献，发现这种共生关系表现出几个伙伴选择的要素，并且可能符合市场范例的要求。最后，我们确定了未来研究的有利可图的问题。
