Dominant predators mediate the impact of habitat size on trophic structure in bromeliad invertebrate communities
Dominant predators mediate the impact of habitat size on trophic structure in bromeliad invertebrate communities
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DOI：
10.1890/14-0304.1
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发表时间：
2015-02-01
期刊：
影响因子：
4.8
通讯作者：
Srivastava, Diane S.
中科院分区：
文献类型：
--
作者：
Petermann, Jana S.;Farjalla, Vinicius F.;Srivastava, Diane S.
局部栖息地的大小已被证明会影响物种在斑块环境中的定殖和灭绝过程。然而，物种在体型、机动性和营养水平上有所不同，对栖息地大小的反应可能不同。到目前为止，我们对栖息地大小如何影响多营养群落的结构以及这种影响在多大程度上可以在广泛的地理范围内推广的理解有限。本文以不同大小的充水凤梨为自然模型系统，研究了生境大小对其无脊椎动物群落营养结构的影响。我们收集了651个凤梨科植物群落的组成和生物量数据，这些群落分布在中美洲和南美洲的8个不同的环境条件、物种池和大型食肉动物的存在。结果表明，群落营养结构随生境（凤梨科）大小的变化而发生显著变化。各样地的腐殖物资源比与生境大小呈一致的负相关。相比之下，捕食者：食腐物（猎物）比例的变化取决于齿形动物作为区域池中优势捕食者的存在。在没有齿形动物的地点，捕食者与食腐动物的生物量比随着栖息地大小的增加而下降。在有熊齿动物的地点，我们发现熊齿动物在大型凤梨科动物中比在小型凤梨科动物中更常见，并且捕食者：碎屑生物生物量比随着栖息地大小的增加而增加，直到一些营养金字塔倒转。我们的研究结果表明，生物量在食物网水平上的分布在很大程度上取决于栖息地的大小，而在很大程度上与环境条件或营养物质种类组成的地理差异无关。然而，区域物种池中大型捕食者的存在可能从根本上改变栖息地大小和营养结构之间的关系。我们的结论是，考虑到优势物种的响应和多营养效应，在预测群落结构沿栖息地大小梯度的变化时可能是关键的。
Local habitat size has been shown to influence colonization and extinction processes of species in patchy environments. However, species differ in body size, mobility, and trophic level, and may not respond in the same way to habitat size. Thus far, we have a limited understanding of how habitat size influences the structure of multitrophic communities and to what extent the effects may be generalizable over a broad geographic range. Here, we used water-filled bromeliads of different sizes as a natural model system to examine the effects of habitat size on the trophic structure of their inhabiting invertebrate communities. We collected composition and biomass data from 651 bromeliad communities from eight sites across Central and South America differing in environmental conditions, species pools, and the presence of large-bodied odonate predators. We found that trophic structure in the communities changed dramatically with changes in habitat (bromeliad) size. Detritivore:resource ratios showed a consistent negative relationship with habitat size across sites. In contrast, changes in predator:detritivore (prey) ratios depended on the presence of odonates as dominant predators in the regional pool. At sites without odonates, predator:detritivore biomass ratios decreased with increasing habitat size. At sites with odonates, we found odonates to be more frequently present in large than in small bromeliads, and predator:detritivore biomass ratios increased with increasing habitat size to the point where some trophic pyramids became inverted. Our results show that the distribution of biomass amongst food-web levels depends strongly on habitat size, largely irrespective of geographic differences in environmental conditions or detritivore species compositions. However, the presence of large-bodied predators in the regional species pool may fundamentally alter this relationship between habitat size and trophic structure. We conclude that taking into account the response and multitrophic effects of dominant, mobile species may be critical when predicting changes in community structure along a habitat-size gradient.