研究亮点:Piccoli,G.C.D.O.,Antiqueira,P.A.P.,Srivastava,D.S.,&Romero,G、Q.(2024)。生态系统内部和整个生态系统的营养级联:反掠夺性防御的作用,捕食者类型和碎屑质量。动物生态学杂志,00,1-14。https://doi.org/10.1111/1365-2656.14063.生态系统功能受自下而上的限制性营养素供应和自上而下的动物反馈效应之间的相互作用控制。然而,动物与营养控制的程度取决于环境。关键挑战在于表征这种背景依赖性,该依赖性被假设取决于动物功能性状的差异。报道一个重要的实验,Piccoli等人。(2014)评估功能不同的捕食者和分解者猎物之间的相互作用如何在自上而下控制模型系统-热带凤梨鱼缸生态系统时创建上下文依赖性。凤眼莲植物在其水箱中蓄水,以支持包含陆地和水生昆虫幼虫和蜘蛛的微观世界生态系统。生态系统由植物凋落物中的营养物质支撑,这些植物凋落物从森林冠层降入水箱。在功能多样的幼虫昆虫分解群落分解后,营养物质会释放,这些幼虫昆虫分解群落的摄食方式和反捕食者防御策略不同。这个分解群落被一种范围狭窄的水生昆虫幼虫捕食者和广泛的蜘蛛捕食者所捕食,它们在水生和周围的陆地生态系统之间交叉。对动物群落进行实验操作,以测试功能多样的猎物群落介导的捕食者的控制程度,包括四种处理方法:(i)具有组成不同功能组但没有捕食者的有害生物的对照,(二)增加了跨生态系统蜘蛛捕食者,(iii)添加了纯粹的水生豆娘幼虫捕食者,(iv)添加了两种捕食者类型,以捕获它们对生态系统功能的相互作用影响(分解,营养释放,和植物生长)。值得注意的是,该研究使用结构方程模型解决了直接和间接控制的因果途径和优势。这些发现揭示了由于捕食者单独和共同克服猎物防御并控制其丰度的不同能力而产生的上下文依赖性,伴随着级联效应,减少并增强了分解和养分释放,以支持凤梨科植物的生产。研究表明,捕食者有一个决定,尽管在质量和数量上不同,手通过对限制性营养素释放的反馈作用来塑造自下而上的控制程度。这项开创性的研究为理解在控制生态系统功能中确定上下文依赖性的机制提供了前进的道路。
Research Highlight: Piccoli, G. C. d. O., Antiqueira, P. A. P., Srivastava, D. S., & Romero, G. Q. (2024). Trophic cascades within and across ecosystems: The role of anti-predatory defences, predator type and detritus quality. Journal of Animal Ecology, 00, 1-14. https://doi.org/10.1111/1365-2656.14063. Ecosystem functioning is controlled by the interplay between bottom-up supply of limiting nutrients and top-down animal feedback effects. However, the degree of animal versus nutrient control is context-dependent. A key challenge lies in characterizing this context dependency which is hypothesized to depend on differences in animal functional traits. Reporting on an important experiment, Piccoli et al. (2014) evaluate how interactions among functionally different
predators and decomposer prey create context dependency in top-down control of a model system-tropical bromeliad tank ecosystems. Bromeliad plants hold water in their tanks supporting microcosm ecosystems containing terrestrial and aquatic insect larvae and arachnids. The ecosystems are supported by nutrients in plant litter that rains down from forest canopies into the tanks. Nutrients are released after litter is decomposed by a functionally diverse community of larval insect decomposers that differ in feeding mode and antipredator defence strategy. This decomposer community is preyed upon by an exclusively narrowly ranging aquatic insect larval predator and widely ranging spider predator that crosses between the aquatic and surrounding terrestrial ecosystems. Experimental manipulation of the animal community to test for the degree of control by
predators mediated by the functionally diverse prey community included four treatments: (i) a control with the detritivores composing different function groups but without
predators, (ii) the cross-ecosystem spider predator added, (iii) the purely aquatic damselfly larvae predator added and (iv) both predator types added to capture their interacting effect on ecosystem function (decomposition, nutrient release, and plant growth). Notably, the study resolved the causal pathways and strengths of direct and indirect control using structural equation modelling. These findings reveal how context dependency arises due to different capacities of the
predators alone and together to overcome prey defences and control their abundances, with attendant cascading effects that diminished as well as enhanced decomposition and nutrient release to support bromeliad plant production. The study reveals that
predators have a decided, albeit qualitatively and quantitatively different, hand in shaping the degree of bottom-up control through feedback effect on the release of limiting nutrients. This ground-breaking study provides a way forward in understanding the mechanisms determining context dependency in the control over ecosystem functioning.