Data from: Light and growth form interact to shape stomatal ratio among British angiosperms

In most plants, stomata are located only on the abaxial leaf surface (hypostomy), but many plants have stomata on both surfaces (amphistomy). High light and herbaceous growth form have been hypothesized to favor amphistomy, but these hypotheses have not been rigorously tested together using phylogenetic comparative methods. I leveraged a large dataset including stomatal ratio, Ellenberg light indicator value, growth form and phylogenetic relationships for 372 species of British angiosperms. I used phylogenetic comparative methods to test how light and/or growth form influence stomatal ratio and density. High light and herbaceous growth form are correlated with amphistomy, as predicted, but they also interact; the effect of light is pronounced in therophytes (annuals) and perennial herbs, but muted in phanerophytes (shrubs and trees). Furthermore, amphistomy and stomatal density evolve together in response to light. Comparative analyses of British angiosperms reveal two major insights. First, light and growth form interact to shape stomatal ratio; amphistomy is common under high light, but mostly for herbs. Second, coordinated evolution of adaxial stomatal density and light tolerance indicates that amphistomy helps to optimally balance light acquisition with gas exchange. Stomatal ratio may have potential as a functional trait for paleoecology and crop improvement.多数植物的气孔仅分布于叶远轴面（abaxial leaf surface），该类气孔分布模式被称为单气孔分布（hypostomy）；但不少植物的气孔同时存在于叶的上下两面，该模式被称为双气孔分布（amphistomy）。此前有假说提出，高光环境与草本生长型更易促成双气孔分布，但目前尚未有研究通过系统发育比较方法（phylogenetic comparative methods）对这两类假说开展联合严谨检验。本研究依托涵盖372种英国被子植物（British angiosperms）的大型数据集，数据集包含气孔比率（stomatal ratio）、埃伦贝格光指示值（Ellenberg light indicator value）、生长型以及系统发育关系等核心信息。本研究采用系统发育比较方法，探究光照条件与/或生长型对气孔比率及气孔密度（stomatal density）的调控作用。正如假说预测，高光环境与草本生长型均与双气孔分布呈显著正相关，且二者存在交互效应：光照对气孔分布的影响在一年生植物（therophytes，即一年生草本）与多年生草本中极为显著，但在高位芽植物（phanerophytes，即灌木与乔木）中则相对微弱。此外，双气孔分布与气孔密度会随光照条件协同演化。针对英国被子植物的系统发育比较分析得出两项核心结论：其一，光照条件与生长型通过交互作用塑造气孔比率；双气孔分布在高光环境下更为常见，但主要见于草本类群。其二，近轴面气孔密度（adaxial stomatal density）与耐光性的协同演化表明，双气孔分布有助于在光能获取与气体交换之间实现最优平衡。气孔比率有望作为古生态学（paleoecology）与作物改良（crop improvement）领域的功能性状加以应用。