Intransitive competition is common across five major taxonomic groups and is driven by productivity, competitive rank and functional traits
Intransitive competition is common across five major taxonomic groups and is driven by productivity, competitive rank and functional traits
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DOI：
10.1111/1365-2745.12959
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发表时间：
2018-05
影响因子：
5.5
通讯作者：
S. Soliveres;A. Lehmann;S. Boch;F. Altermatt;F. Carrara;T. Crowther;M. Delgado‐Baquerizo;Anne Kempel;D. Maynard;M. Rillig;B. Singh;P. Trivedi;E. Allan
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作者：
S. Soliveres;A. Lehmann;S. Boch;F. Altermatt;F. Carrara;T. Crowther;M. Delgado‐Baquerizo;Anne Kempel;D. Maynard;M. Rillig;B. Singh;P. Trivedi;E. Allan
竞争可以是完全分层的，也可以是不可传递的，这种分层程度是由多种因素驱动的，包括环境条件、相关物种的功能特征或竞争网络的拓扑结构。同时分析这些竞争等级驱动因素的研究很少。此外，生物直接竞争或通过干扰竞争争夺资源或空间，在当地社区或跨越栖息地。因此，竞争的驱动因素可能会发生相应的变化，并取决于所研究的分类群。我们首次对主要分类群的成对竞争进行了多分类研究，包括维管植物、苔藓、腐殖真菌、水生原生生物和土壤细菌的实验。我们从包括所有物种以及每种可能的三物种组合（三胞胎）的成对竞争矩阵中评估了竞争不可及性的一般程度。然后，我们研究了哪些物种可能参与竞争循环，以及环境条件、竞争等级和功能性状对非传递竞争的影响。我们发现在所有被研究的分类群中都有一定程度的竞争不可及性，三胞胎中有38%到5%是不可及性的。物种之间竞争等级的差异和更肥沃的条件大大减少了不及物性，由竞争等级差异很大的物种组成的三胞胎不太可能不及物性。与只包含竞争等级的模型相比，包含物种功能特征的模型所解释的差异增加了一倍多。三胞胎的特征均值和方差都会影响它们不可及的几率。然而，性状对竞争的影响和作用方向在不同的分类群之间差异很大，这表明性状对竞争的影响是多种多样的。合成。结果表明，生产力和竞争等级是植物非传递性的主要驱动因素。我们还发现，决定竞争不及性的不仅是每个物种的功能性状，还有其伴生物种的功能性状。非传递性竞争在多个分类群中很常见，但在肥沃条件下或在竞争能力差异较大的物种中可能会减弱。这为预测自然群落中非传递性竞争的普遍性提供了第一步。
Competition can be fully hierarchical or intransitive, and this degree of hierarchy is driven by multiple factors, including environmental conditions, the functional traits of the species involved or the topology of competition networks. Studies simultaneously analysing these drivers of competition hierarchy are rare. Additionally, organisms compete either directly or via interference competition for resources or space, within a local neighbourhood or across the habitat. Therefore, the drivers of competition could change accordingly and depend on the taxa studied. We performed the first multi‐taxon study on pairwise competition across major taxonomic groups, including experiments with vascular plants, mosses, saprobic fungi, aquatic protists and soil bacteria. We evaluated how general is competition intransitivity from the pairwise competition matrix including all species and also for each possible three‐species combination (triplets). We then examined which species were likely to engage in competitive loops and the effects of environmental conditions, competitive rank and functional traits on intransitive competition. We found some degree of competition intransitivity in all taxa studied, with 38% to 5% of triplets being intransitive. Variance in competitive rank between species and more fertile conditions strongly reduced intransitivity, with triplets composed of species differing widely in their competitive ranks much less likely to be intransitive. Including functional traits of the species involved more than doubled the variation explained compared to models including competitive rank only. Both trait means and variance within triplets affected the odds of them being intransitive. However, the traits responsible and the direction of trait effects varied widely between taxa, suggesting that traits can have a wide variety of effects on competition. Synthesis. We evaluated the drivers of competition across multiple taxa and showed that productivity and competitive rank are fundamental drivers of intransitivity. We also showed that not only the functional traits of each species, but also those of the accompanying species, determine competition intransitivity. Intransitive competition is common across multiple taxa but can dampen under fertile conditions or for those species with large variance in their competitive abilities. This provides a first step towards predicting the prevalence of intransitive competition in natural communities.