J.F. Blumenbach Institute of Zoology and Anthropology, Systemic Conservation Biology Group, Georg-August University Goettingen, 37073 Goettingen, Germany.
Ecol Lett. 2011 Feb;14(2):169-78. doi: 10.1111/j.1461-0248.2010.01568.x. Epub 2010 Dec 27.
Despite growing awareness of the significance of body-size and predator-prey body-mass ratios for the stability of ecological networks, our understanding of their distribution within ecosystems is incomplete. Here, we study the relationships between predator and prey size, body-mass ratios and predator trophic levels using body-mass estimates of 1313 predators (invertebrates, ectotherm and endotherm vertebrates) from 35 food-webs (marine, stream, lake and terrestrial). Across all ecosystem and predator types, except for streams (which appear to have a different size structure in their predator-prey interactions), we find that (1) geometric mean prey mass increases with predator mass with a power-law exponent greater than unity and (2) predator size increases with trophic level. Consistent with our theoretical derivations, we show that the quantitative nature of these relationships implies systematic decreases in predator-prey body-mass ratios with the trophic level of the predator. Thus, predators are, on an average, more similar in size to their prey at the top of food-webs than that closer to the base. These findings contradict the traditional Eltonian paradigm and have implications for our understanding of body-mass constraints on food-web topology, community dynamics and stability.
尽管人们越来越意识到体型和捕食者-猎物体质量比对于生态网络稳定性的重要性，但我们对它们在生态系统中的分布的理解还不完整。在这里，我们使用来自 35 个食物网（海洋、溪流、湖泊和陆地）的 1313 种捕食者（无脊椎动物、变温动物和恒温脊椎动物）的体质量估计值，研究了捕食者和猎物大小、体质量比和捕食者营养级之间的关系。在所有生态系统和捕食者类型中，除了溪流（它们在捕食者-猎物相互作用中似乎具有不同的体型结构）之外，我们发现：（1）几何平均猎物质量随捕食者质量呈幂律增长，幂律指数大于 1；（2）捕食者体型随营养级增加而增大。与我们的理论推导一致，我们表明这些关系的定量性质意味着捕食者-猎物体质量比随着捕食者的营养级而系统下降。因此，与靠近底部的猎物相比，处于食物网顶端的捕食者在体型上更相似。这些发现与传统的埃尔顿范式相矛盾，对我们理解体型对食物网拓扑结构、群落动态和稳定性的限制具有重要意义。
