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损失。任何将水分损失降至最低的调整都是以减缓碳吸收为代价的。理论认为，涉及植物形态、生理和叶片结构的大约20个性状应该随着水分供应的不同而不同，以使整个植株的高度生长和存活最大化。这项研究将考察十种桉树(地球上种植最广泛的树属之一)的所有这些特征，它们在澳大利亚维多利亚从温带雨林到半沙漠的降雨梯度上的分布不同。植物将在跨越这一坡度的四个普通花园中种植。将定期测量光合作用和水分运输能力，并将利用定期收获来评估形态和生长速度。这个项目在理解适应水分供应方面是开创性的，因为它结合了一种新的理论方法和普通花园的使用来测试潜在的影响物种分布的因素。该项目将培养一名博士后、至少一名研究生和多名本科生。这一结果将有助于了解干旱地区植物对长期干旱和严重干旱的响应及其分布。关于桉树适应水分供应的多媒体演示将在公共电视上播放，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石田野课程，重点将放在植物适应和群落生态学上。植物生存、生长、适应和涉及光合作用、水力和资源分配的大约20个特征的整合将在澳大利亚维多利亚的十个桉树物种中进行研究，从系统发育的层次和连续的年降雨带的优势来进行研究。测量将在跨越这一坡度的四个普通花园进行两年两年的实验。将进行适应性和功能整合的系统发育结构测试，询问观察到的变化是否倾向于最大限度地提高高度增长速度，物种内响应水分供应的可塑性模式是否与物种之间的可塑性模式相冲突，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主导地位的条件相似的情况下，类群才在高度生长或生存方面具有优势。对每个普通花园的竞争成功的直接实验测试将与基于不拥挤的单一栽培的生长速度和基于植物特征的理论预测的预期进行比较。这项拟议的研究对于研究植物对水分供应的适应是新颖的，就其适应和整合的性状范围而言，使用普通花园来测试高度生长的交叉作为适应的支持和潜在的力量塑造物种分布，以及使用生长模型来确定影响植物生长的关键性状和特征聚集体。

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.