Kummel Miroslav, Salant Stephen W
Department of Environmental Science, Colorado College, Colorado Springs, Colorado 80907, USA.
Ecology. 2006 Apr;87(4):892-902. doi: 10.1890/0012-9658(2006)87[892:teomou]2.0.co;2.
Can choice of mutualistic partners and the degree of their utilization determine (1) mutualistic partner coexistence, (2) relative abundance of mutualistic partners, and (3) environment-dependent changes in relative abundance? We investigate these questions in the context of the plant-mycorrhizal fungal mutualism by building a biological market model potentially applicable to other mutualisms as well. We examine the situation where a single plant selectively utilizes member(s) of a group of ectomycorrhizal potential trading partners. Under biologically realistic circumstances, the plant may simultaneously utilize multiple partners, its degree of utilization determining the community structure of the fungi. If utilization of multiple partners is optimal, the marginal cost of acquiring additional nitrogen from every trading partner must be equal while the marginal cost of acquiring it from any unutilized partner must be larger. Because the plant's nitrogen demand is light dependent, the composition of the fungal species among its trading partners changes along light-availability gradients. We discuss the design of an experiment to test the key prediction of our model, the equalization of marginal cost.
（1）互利共生伙伴的共存；（2）互利共生伙伴的相对丰度；以及（3）相对丰度随环境的变化？我们通过构建一个可能也适用于其他共生关系的生物市场模型，在植物 - 外生菌根真菌共生关系的背景下研究这些问题。我们考察了一种情况，即单一植物选择性地利用一组外生菌根潜在交易伙伴中的成员。在生物学上现实的情况下，植物可能同时利用多个伙伴，其利用程度决定了真菌的群落结构。如果利用多个伙伴是最优的，那么从每个交易伙伴获取额外氮的边际成本必须相等，而从未被利用的伙伴获取氮的边际成本必须更高。由于植物的氮需求取决于光照，其交易伙伴中真菌物种的组成会随着光照可利用性梯度而变化。我们讨论了一个实验的设计，以检验我们模型的关键预测——边际成本均等化。
