Wyatt Gregory A K, Kiers E Toby, Gardner Andy, West Stuart A
Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom.
Evolution. 2014 Sep;68(9):2603-18. doi: 10.1111/evo.12466. Epub 2014 Jul 21.
It has been argued that cooperative behavior in the plant-mycorrhizal mutualism resembles trade in a market economy and can be understood using economic tools. Here, we assess the validity of this "biological market" analogy by investigating whether a market mechanism--that is, competition between partners over the price at which they provide goods--could be the outcome of natural selection. Then, we consider the conditions under which this market mechanism is sufficient to maintain mutualistic trade. We find that: (i) as in a market, individuals are favored to divide resources among trading partners in direct relation to the relative amount of resources received, termed linear proportional discrimination; (ii) mutualistic trade is more likely to be favored when individuals are able to interact with more partners of both species, and when there is a greater relative difference between the species in their ability to directly acquire different resources; (iii) if trade is favored, then either one or both species is favored to give up acquiring one resource directly, and vice versa. We then formulate testable predictions as to how environmental changes and coevolved responses of plants and mycorrhizal fungi will influence plant fitness (crop yields) in agricultural ecosystems.
有人认为，植物与菌根共生关系中的合作行为类似于市场经济中的贸易，并且可以用经济学工具来理解。在此，我们通过研究一种市场机制——即合作伙伴之间就其提供货物的价格进行竞争——是否可能是自然选择的结果，来评估这种“生物市场”类比的有效性。然后，我们考虑这种市场机制足以维持互利贸易的条件。我们发现：（i）与市场情况一样，个体倾向于根据从贸易伙伴那里获得的资源相对数量，按比例在贸易伙伴之间分配资源，这被称为线性比例歧视；（ii）当个体能够与两个物种的更多伙伴进行互动，以及当两个物种在直接获取不同资源的能力上存在更大的相对差异时，互利贸易更有可能受到青睐；（iii）如果贸易受到青睐，那么要么一个物种要么两个物种都倾向于放弃直接获取一种资源，反之亦然。然后，我们就环境变化以及植物和菌根真菌的共同进化反应将如何影响农业生态系统中的植物适应性（作物产量），提出了可检验的预测。
