Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, EE-51014 Tartu, Estonia.
Evolution. 2013 Feb;67(2):583-9. doi: 10.1111/j.1558-5646.2012.01776.x. Epub 2012 Sep 7.
Numerous studies have suggested a general relationship between the degree of host specialization and body size in herbivorous animals. In insects, smaller species are usually shown to be more specialized than larger-bodied ones. Various hypotheses have attempted to explain this pattern but rigorous proof of the body size-diet breadth relationship has been lacking, primarily because the scarceness of reliable phylogenetic information has precluded formal comparative analyses. Explicitly using phylogenetic information for a group of herbivores (geometrid moths) and their host plant range, we perform a comparative analysis to study the body size-diet breadth relationship. Considering several alternative measures of body size and diet breadth, our results convincingly demonstrate without previous methodological issues-a first for any taxon-a positive association between these traits, which has implications for evaluating various central aspects of the evolutionary ecology of herbivorous insects. We additionally demonstrate how the methods used in this study can be applied in assessing hypotheses to explain the body size-diet breadth relationship. By analyzing the relationship in tree-feeders alone and finding that the positive relationship remains, the result suggests that the body size-diet breadth relationship is not solely driven by the type of host plant that species feed on.
大量研究表明，草食性动物的宿主专化程度与体型大小之间存在普遍关系。在昆虫中，较小的物种通常比较大体型的物种更为特化。各种假说试图解释这种模式，但由于缺乏可靠的系统发育信息，对体型-食性广度关系的严格证明一直缺乏，主要是因为缺乏可靠的系统发育信息，无法进行正式的比较分析。我们明确地使用了一组草食性动物（尺蠖蛾）及其寄主植物范围的系统发育信息，进行了比较分析，以研究体型-食性广度关系。考虑到体型和食性广度的几种替代度量，我们的结果令人信服地证明了，在任何分类群中，这两个特征之间都存在正相关关系，而没有以前方法学上的问题，这对评估草食性昆虫进化生态学的各个核心方面具有重要意义。我们还展示了如何在评估解释体型-食性广度关系的假说时应用本研究中使用的方法。通过单独分析树栖食者的关系，并发现这种正相关关系仍然存在，结果表明，体型-食性广度关系不仅仅是由物种所食用的寄主植物类型驱动的。
