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...

在多数植物中，气孔仅分布于叶片远轴面（abaxial leaf surface），这类气孔分布模式被称为下生气孔型（hypostomy）；但许多植物的气孔同时存在于叶片两面，此模式为双生气孔型（amphistomy）。此前有假说提出，高光环境与草本生长型更倾向于促成双生气孔型，但这类假说尚未通过系统发育比较方法（phylogenetic comparative methods）开展联合严格检验。
本研究依托涵盖372种英国被子植物的大型数据集，其中包含气孔比例、埃伦伯格光指示值（Ellenberg light indicator value）、生长型以及系统发育关系等数据；并采用系统发育比较方法，检验光照条件及/或生长型对气孔比例与气孔密度的影响。
研究结果显示，高光环境与草本生长型确实如假说所预测的那样与双生气孔型呈显著相关，且二者存在交互效应：光照对气孔分布模式的影响在一年生植物（therophytes）与多年生草本中较为显著，但在高位芽植物（phanerophytes，即灌木与乔木）中则被弱化。此外，双生气孔型与气孔密度会协同响应光照条件发生演化。
对英国被子植物的比较分析揭示了两项核心研究发现……