School of Life and Health Sciences, Whitelands College, University of Roehampton, London, SW15 4JD, UK.
Max Planck Institute for Mathematics in the Sciences, Leipzig, 04103, Germany.
Nat Commun. 2022 Aug 25;13(1):4990. doi: 10.1038/s41467-022-32578-5.
The ratio of predator-to-prey biomass is a key element of trophic structure that is typically investigated from a food chain perspective, ignoring channels of energy transfer (e.g. omnivory) that may govern community structure. Here, we address this shortcoming by characterising the biomass structure of 141 freshwater, marine and terrestrial food webs, spanning a broad gradient in community biomass. We test whether sub-linear scaling between predator and prey biomass (a potential signal of density-dependent processes) emerges within ecosystem types and across levels of biological organisation. We find a consistent, sub-linear scaling pattern whereby predator biomass scales with the total biomass of their prey with a near ¾-power exponent within food webs - i.e. more prey biomass supports proportionally less predator biomass. Across food webs, a similar sub-linear scaling pattern emerges between total predator biomass and the combined biomass of all prey within a food web. These general patterns in trophic structure are compatible with a systematic form of density dependence that holds among complex feeding interactions across levels of organization, irrespective of ecosystem type.
捕食者-猎物生物量的比例是营养结构的一个关键要素，通常从食物链的角度进行研究，而忽略了可能支配群落结构的能量传递渠道（例如杂食性）。在这里，我们通过描述 141 个淡水、海洋和陆地食物网的生物量结构来解决这一缺陷，这些食物网跨越了群落生物量的广泛梯度。我们测试了在生态系统类型和生物组织层次上，捕食者和猎物生物量之间是否存在亚线性比例关系（密度依赖过程的潜在信号）。我们发现了一种一致的、亚线性的比例关系模式，即捕食者生物量与猎物的总生物量呈近 ¾ 幂指数关系，即在食物网中，更多的猎物生物量支持相对较少的捕食者生物量。在食物网中，总捕食者生物量与食物网中所有猎物的总生物量之间也出现了类似的亚线性比例关系。这些营养结构的一般模式与组织层次上复杂的摄食相互作用之间存在系统形式的密度依赖性是一致的，而与生态系统类型无关。
