Data from: Degree of specialization is related to body size in herbivorous insects: a phylogenetic confirmation

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.诸多研究均证实，植食性动物的宿主特化程度与其体型大小间存在一般性关联。在昆虫类群中，体型较小的物种通常较体型较大的物种具备更高的宿主特化程度。已有多种假说尝试阐释这一规律，但学界始终缺乏针对体型与食性广度（diet breadth）二者关联的严谨实证，核心症结在于可靠系统发育（phylogenetic）信息的匮乏，使得正式的比较分析难以开展。本研究明确利用一类植食性动物——尺蛾类（geometrid moths）——及其宿主植物范围的系统发育信息，开展比较分析以探究体型与食性广度间的关联。本研究综合考量了体型与食性广度的多种替代测度指标，结果确凿地证实二者间存在正向关联——这是首次在任意生物类群中规避此前的方法学缺陷并完成此类验证——该发现对评估植食性昆虫进化生态学的多项核心议题具有重要参考价值。此外，本研究还阐明了本次研究所用方法可如何应用于验证解释体型与食性广度关联的各类假说。仅针对取食木本植物的类群开展关联分析后，仍得到了正向关联的结果，这表明体型与食性广度间的关联并非仅由物种所取食的宿主植物类型所驱动。