School of Biological Sciences and the Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia.
Ecol Lett. 2013 Jul;16(7):895-902. doi: 10.1111/ele.12116. Epub 2013 May 23.
Understanding why food chains are relatively short in length has been an area of research and debate for decades. We tested if progressive changes in the nutritional content of arthropods with trophic position limit the availability of a key nutrient, lipid, for carnivores. Arthropods at higher trophic levels had progressively less lipid and more protein in their bodies compared with arthropods at lower trophic levels. The nutrients present in arthropod bodies were directly related to the nutrients that predators extracted when feeding on those arthropods. As a consequence, nutrient assimilation shifted from lipid-biased to protein-biased as arthropods ascended trophic levels from herbivores to secondary carnivores. Successive changes in the nutritional consequences of predation may ultimately set an upper limit on the number of trophic levels in arthropod communities. Further work is needed to examine the influence of lipid and other nutrients on food web traits in a range of ecosystems.
理解为什么食物链的长度相对较短一直是研究和争论的领域。我们测试了随着营养水平的提高，节肢动物的营养成分是否会限制关键营养素脂质的可利用性，而脂质是肉食动物的关键营养素。与低营养水平的节肢动物相比，高营养水平的节肢动物体内的脂质逐渐减少，而蛋白质逐渐增加。节肢动物体内的营养物质与捕食者在捕食这些节肢动物时提取的营养物质直接相关。因此，随着节肢动物从草食动物到二级肉食动物在营养水平上的上升，营养物质的同化作用从偏向脂质转变为偏向蛋白质。捕食的营养后果的连续变化可能最终限制了节肢动物群落中营养水平的数量上限。需要进一步研究脂质和其他营养物质对一系列生态系统中食物网特征的影响。
