Collaborative Research: The Evolution of Leaf Form in Viburnum (Adoxaceae)

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”陆生植物在叶片形态的许多方面表现出显著的变异。叶片是光合作用的主要场所，因此是植物生长和最终健康的主要保管人。先前的研究表明，在特定的环境中，特定的叶片性状存在最优值，从而使生长最大化，从而预测某些叶片形式将在特定条件下进化。然而，对外部压力（如气候）的进化反应可能受到限制，因为叶片是整个植物发育和功能的组成部分。尽管长期以来人们对叶片在植物生态适应中的作用感兴趣，但很少有研究成功地记录了叶片性状与环境相关的一致进化变化。该合作项目将开发Viburnum （Adoxaceae）植物谱系，这是一个大约168种木本灌木和乔木的广泛群体，作为研究叶片形态生态学和进化的模型系统。Viburnum是解决这个问题的理想选择，因为它展示了叶片形状和大小的显著多样性，而且关于该群体内部的进化关系，我们已经知道了很多。跨学科的PI团队将从两个常见的花园收集生理数据，从植物标本馆收集解剖学和环境数据，以及用于系统发育分析的分子序列数据，以产生一个独特的，完整的叶片进化视角，同时详细和广泛。他们将直接测试一些关于茎和叶共同进化的假设，叶片水分利用的某些方面与光合能力的解耦，以及响应环境条件的特定叶片性状的进化。一种预测是，相当大的叶片形状多样性是在相对狭窄的气候空间内进化的，这表明其他因素在塑造叶片结构和功能的进化轨迹方面历史上更为重要。这项工作的结果可能与预测植物对快速气候变化的响应直接相关。这项工作还将导致新的在线社区教学和研究资源的发展，例如用于解剖研究的大型树叶收集。PI还将与皮博迪自然历史博物馆和来自罗德岛普罗维登斯地区的公立学校教师合作，开发两个针对纽黑文和普罗维登斯学区小学和高中水平的“树叶多样性”教育模块。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Terrestrial plants display remarkable variation in many aspects of leaf form. Leaves serve as main sites for photosynthesis, and are thus primary custodians of plant growth and ultimately, fitness. Previous work suggests that there are optimal values for particular leaf traits in a given environment that will maximize growth, and thus predicts that certain leaf forms will evolve under certain conditions. However, evolutionary response to external pressures such as climate may be constrained, because leaves are developmentally and functionally integrated parts of the whole plant. In spite of the long-standing interest in the role of leaves in plant ecological adaptation, few studies have successfully documented consistent evolutionary shifts in leaf traits in relation to environment. This collaborative project will develop the plant lineage Viburnum (Adoxaceae), a widespread group of approximately 168 species of woody shrubs and trees, as a model system for investigations into the ecology and evolution of leaf form. Viburnum is ideally suited for this problem as it exhibits a remarkable diversity of leaf shapes and sizes, and much is already known regarding evolutionary relationships within the group. The interdisciplinary PI team will collect physiological data from two common gardens, anatomical and environmental data from herbarium collections, and molecular sequence data for phylogenetic analyses to produce a unique, whole-lineage perspective on leaf evolution that is simultaneously detailed and broad. They will directly test several hypotheses regarding stem and leaf co-evolution, the decoupling of certain aspects of leaf water use from photosynthetic capacity, and the evolution of particular leaf traits in response to environmental conditions. One prediction is that considerable leaf shape diversity has evolved within a relatively narrow climate space, suggesting that other factors have historically been more important in shaping the evolutionary trajectory of leaf structure and function. Results from this work may be directly relevant to predicting plant response to rapid climate change. This work will also result in the development of new online community-wide teaching and research resources, such as a large leaf collection for anatomical study. In conjunction with the Peabody Museum of Natural History and public school teachers from the Providence, RI area, the PI's will also develop two 'leaf diversity' education modules targeted for elementary and high school levels in the New Haven and Providence school districts.