Zook Alexander E, Eklof Anna, Jacob Ute, Allesina Stefano
Department of Ecology and Evolution, University of Chicago, United States.
Institute for Hydrobiologie and Fisheries Science, University Hamburg, Germany.
J Theor Biol. 2011 Feb 21;271(1):106-13. doi: 10.1016/j.jtbi.2010.11.045. Epub 2010 Dec 7.
Food webs, the networks describing "who eats whom" in an ecosystem, are nearly interval, i.e. there is a way to order the species so that almost all the resources of each consumer are adjacent in the ordering. This feature has important consequences, as it means that the structure of food webs can be described using a single (or few) species' traits. Moreover, exploiting the quasi-intervality found in empirical webs can help build better models for food web structure. Here we investigate which species trait is a good proxy for ordering the species to produce quasi-interval orderings. We find that body size produces a significant degree of intervality in almost all food webs analyzed, although it does not match the maximum intervality for the networks. There is also a great variability between webs. Other orderings based on trophic levels produce a lower level of intervality. Finally, we extend the concept of intervality from predator-centered (in which resources are in intervals) to prey-centered (in which consumers are in intervals). In this case as well we find that body size yields a significant, but not maximal, level of intervality. These results show that body size is an important, although not perfect, trait that shapes species interactions in food webs. This has important implications for the formulation of simple models used to construct realistic representations of food webs.
食物网，即描述生态系统中“谁吃谁”的网络，几乎是区间性的，也就是说，存在一种对物种进行排序的方法，使得每个消费者的几乎所有资源在排序中都是相邻的。这一特征具有重要影响，因为这意味着食物网的结构可以用单一（或少数）物种的特征来描述。此外，利用经验食物网中发现的准区间性有助于构建更好的食物网结构模型。在这里，我们研究哪种物种特征是对物种进行排序以产生准区间排序的良好代理。我们发现，体型在几乎所有分析的食物网中都产生了显著程度的区间性，尽管它与网络的最大区间性不匹配。不同食物网之间也存在很大差异。基于营养级的其他排序产生的区间性水平较低。最后，我们将区间性的概念从以捕食者为中心（其中资源处于区间）扩展到以猎物为中心（其中消费者处于区间）。在这种情况下，我们同样发现体型产生了显著但非最大程度的区间性。这些结果表明，体型是塑造食物网中物种相互作用的一个重要但并不完美的特征。这对于用于构建食物网现实表征的简单模型的制定具有重要意义。
