Applying modern coexistence theory to priority effects
Applying modern coexistence theory to priority effects
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DOI：
10.1073/pnas.1803122116
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发表时间：
2019-03-26
影响因子：
11.1
通讯作者：
Fukami, Tadashi
中科院分区：
文献类型：
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作者：
Grainger, Tess Nahanni;Letten, Andrew D.;Fukami, Tadashi
现代共存理论越来越多地用于解释竞争物种之间的差异如何导致共存而不是竞争排斥。尽管检验这一理论的研究主要集中在竞争排斥的确定性案例上，即同一物种总是获胜，但越来越多的证据表明，竞争排斥往往是历史偶然的，例如，无论哪个物种碰巧先到达，都会排除另一个物种。共存理论预测，当大的不稳定差异（竞争者的正频率依赖增长率）与小的适应性差异（竞争者的内在增长率和对竞争的敏感性差异）相结合时，历史上的偶然排斥，即优先效应，将发生，创造条件，使两个物种都不能入侵其竞争者的既定种群。在这里，我们扩展了现代共存理论的经验应用，以确定促进优先效应的条件。我们进行了成对的入侵测试与四株花蜜殖民酵母，以确定如何驱动优先效应的不稳定和健身差异改变了两个非生物因素的花蜜环境特征：糖浓度和pH值。我们发现，较高的糖浓度增加了优先效应的可能性，通过减少竞争物种之间的健身差异。相比之下，较高的pH值并没有改变优先效应的可能性，而是通过使适应性差异和不稳定差异接近于零，使竞争更加中性。这项研究展示了优先效应到适应性和不稳定成分的经验划分如何阐明环境条件塑造竞争相互作用的途径。
Modern coexistence theory is increasingly used to explain how differences between competing species lead to coexistence versus competitive exclusion. Although research testing this theory has focused on deterministic cases of competitive exclusion, in which the same species always wins, mounting evidence suggests that competitive exclusion is often historically contingent, such that whichever species happens to arrive first excludes the other. Coexistence theory predicts that historically contingent exclusion, known as priority effects, will occur when large destabilizing differences (positive frequency-dependent growth rates of competitors), combined with small fitness differences (differences in competitors' intrinsic growth rates and sensitivity to competition), create conditions under which neither species can invade an established population of its competitor. Here we extend the empirical application of modern coexistence theory to determine the conditions that promote priority effects. We conducted pairwise invasion tests with four strains of nectar-colonizing yeasts to determine how the destabilizing and fitness differences that drive priority effects are altered by two abiotic factors characterizing the nectar environment: sugar concentration and pH. We found that higher sugar concentrations increased the likelihood of priority effects by reducing fitness differences between competing species. In contrast, higher pH did not change the likelihood of priority effects, but instead made competition more neutral by bringing both fitness differences and destabilizing differences closer to zero. This study demonstrates how the empirical partitioning of priority effects into fitness and destabilizing components can elucidate the pathways through which environmental conditions shape competitive interactions.