The 'filtering' metaphor revisited: competition and environment jointly structure invasibility and coexistence
The 'filtering' metaphor revisited: competition and environment jointly structure invasibility and coexistence
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DOI：
10.1098/rsbl.2018.0460
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发表时间：
2018-08-01
期刊：
影响因子：
3.3
通讯作者：
Gilbert, Benjamin
中科院分区：
文献类型：
--
作者：
Germain, Rachel M.;Mayfield, Margaret M.;Gilbert, Benjamin
“过滤”，或者说物种多样性的减少，是因为并非所有物种都能在所有地点持续存在而发生的，被认为是分层展开的，在大尺度上受到环境的控制，在小尺度上受到竞争的控制。然而，竞争和环境的生态效应并不是独立的，观察方法排除了对其相互作用的研究。我们使用人口统计方法对 30 种植物进行实验测试：(i) 竞争对两种土壤湿度环境中物种持久性的影响，以及 (ii) 环境条件对竞争共存机制的影响。我们发现，即使在没有竞争的情况下缺乏影响，竞争者也会导致不同环境中物种的持久性差异，并且决定持久性的特征取决于竞争环境。如果我们的研究是观察性的和基于性状的，我们就会错误地得出结论：环境过滤了生物量低、根浅和种子小的物种。环境条件的变化对共存结果产生了特殊的影响，增加了对某些物种的竞争排斥，同时促进了其他物种的共存。我们的结果强调了根据竞争而不是孤立地考虑环境过滤的重要性，并挑战群落组装模型和预测未来物种分布的方法。
'Filtering', or the reduction in species diversity that occurs because not all species can persist in all locations, is thought to unfold hierarchically, controlled by the environment at large scales and competition at small scales. However, the ecological effects of competition and the environment are not independent, and observational approaches preclude investigation into their interplay. We use a demographic approach with 30 plant species to experimentally test: (i) the effect of competition on species persistence in two soil moisture environments, and (ii) the effect of environmental conditions on mechanisms underlying competitive coexistence. We find that competitors cause differential species persistence across environments even when effects are lacking in the absence of competition, and that the traits which determine persistence depend on the competitive environment. If our study had been observational and trait-based, we would have erroneously concluded that the environment filters species with low biomass, shallow roots and small seeds. Changing environmental conditions generated idiosyncratic effects on coexistence outcomes, increasing competitive exclusion of some species while promoting coexistence of others. Our results highlight the importance of considering environmental filtering in the light of, rather than in isolation from, competition, and challenge community assembly models and approaches to projecting future species distributions.