Comparison of size-structured and species-level trophic networks reveals antagonistic effects of temperature on vertical trophic diversity at the population and species level

It is predicted that warmer conditions should lead to a loss of trophic levels, as larger bodied consumers, which occupy higher trophic levels, experience higher metabolic costs at high temperature. Yet, it is unclear whether this prediction is consistent with the effect of warming on the trophic structure of natural systems. Furthermore, effects of temperature at the species level, which arise through a change in species composition, may differ from those at the population level, which arise through a change in population structure. We investigate this by building species-level trophic networks, and size-structured trophic networks, as a proxy for population structure, for 18,648 stream fish communities, from 4,145,234 individual fish samples, across 7,024 stream locations in France from 1980 to 2008. We estimated effects of temperature on total trophic diversity (total number of nodes), vertical trophic diversity (mean and maximum trophic level), and distribution of biomass across tro...

已有研究预测，气候变暖将导致营养级（trophic level）减少，因为体型较大、处于较高营养级的消费者在高温环境下会面临更高的代谢成本（metabolic cost）。然而，目前尚不清楚该预测是否与气候变暖对自然生态系统营养结构的影响相符。此外，由物种组成改变引发的物种水平温度效应，与由种群结构变化引发的种群水平温度效应可能存在差异。本研究针对1980年至2008年间法国7024个溪流点位的18648个溪流鱼类群落（基于4145234尾鱼类个体样本），通过构建物种水平营养网络（trophic network）以及以体型结构化营养网络作为种群结构的替代指标，对该问题展开研究。我们评估了温度对总营养多样性（节点总数）、垂直营养多样性（平均营养级与最大营养级）以及生物量在营养...的分布的影响。