From intra-individual regulation of metabolism to entire ecosystem functioning, the thousands of biogenic compounds produced by organisms serve as a major component of ecological and evolutionary diversity mediating interactions across scales. Earlier work considers canonical reactions, defined as reactions specified along accepted (experimentally validated or theoretically postulated) biosynthetic pathways, as the primary form of constraint on chemical diversity. An emerging understanding of non-canonical reactions (reactions which occur independently of canonical reactions) suggests that the physical chemistry of compounds may play a larger role in constraining chemo-diversity than previously thought. We selected 24 studies of plant volatile profiles, satisfying a defined set of criteria, to assess the extent of correlation among profiles attributable to either shared biosynthetic enzymes or physiochemical properties. Across studies, regardless of treatment, 0.17 (± 0.16 SD) adjusted R² was attributed to both shared biosynthetic enzymes and physiochemical properties; however, there were no significant differences between the amount of unique variance attributed to shared enzymes (0.05 ± 0.08 SD) or physiochemical properties (0.03 ± 0.06 SD). The amount of unique variance explained by physiochemical properties, independent of their canonical relationships, provides a metric for evaluating the role of non-enzymatic and non-canonical reactions in constraining molecular diversity.

从个体内部的代谢调节到整个生态系统的功能，由生物体产生的成千上万的生物化合物是生态和进化多样性的重要组成部分，介导了各个尺度的相互作用。较早的工作将规范反应定义为沿公认的（经实验验证或理论上假定的）生物合成途径指定的反应，这是对化学多样性进行限制的主要形式。对非规范反应（独立于规范反应发生的反应）的新兴理解表明，化合物的物理化学在限制化学多样性方面可能比以前认为的发挥更大的作用。我们选择了24种植物挥发物谱研究，满足一组定义的标准，评估归因于共有生物合成酶或理化特性的谱之间的相关程度。在所有研究中，无论治疗如何，均调整为0.17（±0.16 SD）R ²归因于共有的生物合成酶和理化特性；但是，归因于共享酶的独特变异量（0.05±0.08 SD）或理化特性（0.03±0.06 SD）之间没有显着差异。由理化性质解释的唯一方差量，独立于其典范关系，为评估非酶促和非典范反应在限制分子多样性中的作用提供了一种度量标准。