Raw data from The importance of sampling standardization for comparisons of insect herbivory in deep time: a case study from the late Paleozoic

Sampling standardization has not been fully addressed for the study of insect herbivory in the fossil record. The effects of sampling within a single locality were explored almost a decade ago, but the importance of sampling standardization for comparisons of herbivory across space and time has not yet been evaluated. Here, we present a case study from the Permian in which we evaluate the impact of sampling standardization on comparisons of insect herbivory from two localities that are similar in age and floral composition. Comparisons of insect damage type (DT) diversity change dramatically when the number of leaves examined is standardized by surface area. This finding suggests that surface area should always be taken into account for comparisons of DT diversity. In addition, the three most common metrics of herbivory—DT diversity, proportion of leaves herbivorized and proportion of leaf surface area herbivorized—are inherently decoupled from each other. The decoupling of the diversity and intensity of insect herbivory necessitates a reinterpretation of published data because they had been conflated in previous studies. Future studies should examine the divergent ecological factors that underlie these metrics. We conclude with suggestions to guide the sampling and analysis of herbivorized leaves in the fossil record.

针对化石记录中的昆虫植食性研究，采样标准化的相关议题尚未得到充分解决。近十年前，学界已针对单一化石产地内的采样效应开展了相关探索，但采样标准化对于跨时空植食性对比研究的重要性，至今仍未得到评估。本研究在此呈现一项来自二叠纪（Permian）的案例研究，借此评估采样标准化对两处年代与植物区系组成均相近的化石产地的昆虫植食性对比结果的影响。当以叶表面积为基准对采样叶片数量进行标准化处理后，昆虫损伤类型（Damage Type, DT）多样性的对比结果会发生显著变化。该研究结果表明，在开展DT多样性对比研究时，应始终将叶表面积纳入考量范畴。此外，三类最常用的植食性量化指标——DT多样性、受植叶片占比及受植叶表面积占比——本质上彼此相互脱耦。昆虫植食性多样性与强度的脱耦现象，要求学界重新解读已发表的相关数据，因为此前的研究曾将这二者混为一谈。未来的研究应深入探究支撑这三类指标的差异化生态驱动因子。最后，我们提出相关建议，以指导化石记录中受植叶片的采样与分析工作。