Department of Botany and Molecular Evolution, Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, D-60325, Frankfurt am Main, Germany.
Institute of Ecology, Evolution and Diversity, Goethe-University, Max-von-Laue-Str. 13, D-60439, Frankfurt am Main, Germany.
New Phytol. 2017 Apr;214(1):473-486. doi: 10.1111/nph.14382. Epub 2016 Dec 22.
Vein networks that disobey the global scaling of major vein density with leaf size shed light on functional constraints of vein network formation in dicotyledons. Understanding their evolution, distribution and impact on vein-stomata-climate associations is an important contribution to our global view of vein network organization. Based on vein traits of 55 species of pantropical Ochnaceae, stomata and climatic niche data, and a dated molecular phylogeny, we unveil major structural shifts in vein networks through deep time, relationships between leaf size, vein and stomata traits, and their interplay with climate. Dense 2° veins, reduction of minor veins and the associated breakdown of vein-leaf size scaling evolved multiple times independently in Ochnaceae. In spite of the drastic changes in vein architecture in this venation type, vein and stomatal densities remain correlated. Our study demonstrates that shortening the major vein-stomata distance is economically not less advantageous than by increasing minor vein density, as illustrated by the same degree of coordination between vein and stomatal densities and the similar construction costs across networks with dense 2° veins and those with 'normally' spaced 2° veins.
违反主要叶脉密度随叶面积全球尺度规律的叶脉网络，为双子叶植物叶脉网络形成的功能约束提供了新的认识。了解它们的进化、分布及其对叶脉-气孔-气候关系的影响，是我们全面了解叶脉网络组织的一个重要贡献。基于热带泛生 Ochnaceae 55 种植物的叶脉特征、气孔和气候生态位数据以及一个已发表的分子系统发育，我们揭示了叶脉网络在深层时间上的主要结构变化，以及叶片大小、叶脉和气孔特征之间的关系，以及它们与气候的相互作用。密集的 2°叶脉、次要叶脉的减少以及相关的叶脉-叶面积比例的破坏，在 Ochnaceae 中多次独立进化。尽管这种脉序类型的叶脉结构发生了剧烈变化，但叶脉和气孔密度仍然相关。我们的研究表明，缩短主要叶脉-气孔距离在经济上并不比增加次要叶脉密度更不利，这可以通过叶脉和气孔密度之间相同的协调性以及具有密集 2°叶脉和具有“正常”间隔 2°叶脉的网络的相似构建成本来体现。
