Integrated Adaptations to Moisture Supply and Cross-over in Whole-plant Growth among Eucalyptus Species Along an Australian Rainfall Gradient

陆地植物面临着一个基本的权衡：为了获得光合作用和生长所需的二氧化碳，它们必须将潮湿的活细胞暴露在干燥的大气中，这会导致大量的水分流失。任何减少水流失的调整都是以减缓碳摄入为代价的。理论表明，大约20个涉及植物形态，生理和叶片结构的性状应随水分供应而变化，以最大限度地提高全株高度生长和存活。这项研究将检查所有这些特征的10种桉树（地球上最广泛种植的树木属之一），不同的分布在整个降雨梯度从温带雨林到半沙漠在维多利亚，澳大利亚。植物将种植在四个共同的花园，跨越这个梯度。将定期测量光合和水运输能力，并定期收获，以评估形态和生长速度。该项目是了解适应水分供应的先驱，因为它结合了一种新的理论方法与使用常见的花园来测试潜在的力量塑造物种分布。这个项目将培养一名博士后，至少一名研究生和多名本科生。研究结果将有助于了解植物对长期和严重干旱的反应，以及在干旱地区的分布。将为公共电视台制作关于桉树适应水分供应的多媒体演示，并将通过威斯康星大学麦迪逊分校和悉尼大学提供一个顶点实地课程，重点是植物适应和社区生态学。植物生存，生长，适应和大约20个性状的整合，涉及光合作用，水力学和资源分配将在10个桉树物种中进行研究，在澳大利亚的维多利亚，由连续的年降雨量带的优势而成层。 测量将在两个2年的实验在四个共同的花园跨越这个梯度。将进行系统发育结构的适应和功能整合测试，询问观察到的变化是否倾向于最大化高度生长率，物种内对水分供应的可塑性模式是否与跨物种的模式相冲突，以及物种是否显示出适应性交叉的证据，只有在与它们在自然界中占优势的条件相似的条件下，分类群才在高度生长或存活方面具有优势。 在每个共同的花园竞争成功的直接实验测试将进行比较，根据不拥挤的单一栽培的增长率和理论预测的基础上，植物性状的预期。拟议的研究是新颖的研究植物适应水分供应，在一系列的性状，其适应和整合将被检查，使用常见的花园测试交叉的高度增长作为支持适应和潜在的力量塑造物种分布，并使用生长模型，以确定影响植物生长的关键性状和性状聚集。

Land plants face a fundamental tradeoff: to acquire the carbon dioxide needed to photosynthesize and grow, they must expose their moist, living cells to a dry atmosphere, which causes enormous losses of water. Any adjustment to minimize water loss comes at the price of slower intake of carbon. Theory suggests that roughly 20 traits involving plant morphology, physiology, and leaf structure should vary with moisture supply in order to maximize whole-plant height growth and survival. This study will examine all these traits in ten species of Eucalyptus (one of the most widely planted genera of trees on Earth) that differ in their distribution across a rainfall gradient from temperate rain forest to semi-desert in Victoria, Australia. Plants will be grown in four common gardens that span this gradient. Measurements of photosynthetic and water transport capacity will be made regularly and periodic harvests will be used to assess morphology and rates of growth. This project is pioneering for understanding adaptation to moisture supply, because it combines a novel theoretical approach with the use of common gardens to test for potential forces shaping species distributions. This project will train a postdoc, at least one graduate student, and multiple undergraduates. The results will help to understand plant response to prolonged and severe droughts, and distribution in arid regions. A multimedia presentation on Eucalyptus adaptation to moisture supply will be made for public television, and a capstone field course will be offered through UW-Madison and U Sydney that will focus on plant adaptation and community ecology.Plant survival, growth, adaptation, and integration of roughly 20 traits involving photosynthesis, hydraulics, and resource allocation will be studied in ten Eucalyptus species, stratified phylogenetically and by dominance of successive bands of annual rainfall in Victoria, Australia. Measurements will be made over two 2-year experiments at four common gardens spanning this gradient. Phylogenetically structured tests of adaptation and functional integration will be conducted, asking whether the observed shifts tend to maximize rates of height growth, whether patterns of plasticity within species in response to moisture supply conflict with those seen across species, and whether species show evidence of adaptive cross-over, with taxa having an advantage in height growth or survival only under conditions similar to those they dominate in nature. A direct experimental test of competitive success at each common garden will be compared with expectations based on growth rates of uncrowded monocultures and theoretical predictions based on plant traits. The proposed research is novel for studying plant adaptation to moisture supply, in terms of the range of traits whose adaptation and integration will be examined, the use of common gardens to test for cross-over in height growth as support for adaptation and a potential force shaping species distributions, and the use of growth models to identify key traits and trait aggregates that affect plant growth.