Ecology and Evolution of Photosynthetic Light Responses in the Hawaiian Lobelioids

夏威夷半边莲光合光反应的生态学和进化

• 批准号: 9904366
• 负责人: Thomas Givnish
• 金额: $ 42.8万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-15 至 2003-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904366&HistoricalAwards=false
• 关键词: Ecology; Evolution; Photosynthetic; Light; Responses

The Hawaiian lobelioids are one of the most spectacular examples of ecological diversification among plants. These woody plants occur in alpine bogs, dry sea cliffs, moist scrub, and tropical rainforest interiors and edges, and display a striking variety in growth form and leaf morphology. Based on the PIs' DNA family tree for this group, these plants appear to have invaded densely shaded habitats from the open, sunny sites they occupied before and shortly after their ancestors colonized Hawaii. The central aim of this project is to understand how plants acquire photosynthetic adaptations to sunny vs. shady conditions. The PIs will attempt to reconstruct changes in photosynthetic physiology, leaf form, biochemistry, and whole-plant growth that occurred when shady habitats were invaded from open sites. Species representing groups of related Hawaiian lobelioids, including species of relatively open habitats and closely related species that have more recently invaded deeper shade, will be studied. Field studies will be conducted to characterize the natural light environments of each study species and to measure their response in leaf form and photosynthesis to light availability under natural conditions. Greenhouse studies will be conducted to determine the extent to which different lobeliads show genetic differences in photosynthetic response, leaf traits, and whole-plant growth under different light regimes. Furthermore, these studies will reveal whether species of different habitats respond to variation in light in ways thought to be advantageous (e.g., do species of sunny habitats have photosynthetic rates and leaf traits that tend to increase growth in brightly lit environments at the cost of relatively poor growth in the shade (and vice versa for species of shaded habitats), and whether understory species - which inhabit a light environment that is patchy and relatively unpredictable - show more ability to alter their photosynthetic form and physiology in response to changed light conditions than species of more open habitats. When combined with information on the evolutionary relationships among the study species, this information will tell us what changes occurred at different stages in the invasion of shaded habitats, what characteristics appear to be adaptive to shady environments, and what characteristics appear to be constrained by the evolutionary history of the different groups.This research will allow the PIs to investigate, for the first time, the rise of photosynthetic adaptations to sun vs. shade in a historical framework. The results should increase our understanding of the ecological constraints on photosynthetic performance in plants generally, and of the habitat requirements for lobelioids specifically, many species of which have become quite rare.

夏威夷半边莲是植物中生态多样化最引人注目的例子之一。这些木本植物生长在高山沼泽、干燥的海崖、潮湿的灌木丛以及热带雨林的内部和边缘，并在生长形式和叶子形态上表现出惊人的多样性。根据 PI 的 DNA 族谱，这些植物似乎是从它们的祖先殖民夏威夷之前和之后不久占据的开阔、阳光充足的地方侵入了浓密的阴影栖息地。该项目的中心目标是了解植物如何获得对阳光和阴凉条件的光合作用适应。 PI 将尝试重建当阴凉栖息地从开放地点入侵时发生的光合生理学、叶子形态、生物化学和整个植物生长的变化。 将研究代表相关夏威夷半边形群体的物种，包括相对开放的栖息地的物种和最近侵入更深阴影的密切相关的物种。 将进行实地研究，以表征每个研究物种的自然光环境，并测量它们在自然条件下叶片形状和光合作用对光可用性的响应。 将进行温室研究，以确定不同半边莲在不同光照条件下在光合作用反应、叶子性状和整个植物生长方面表现出遗传差异的程度。 此外，这些研究将揭示不同栖息地的物种是否以被认为有利的方式对光的变化作出反应（例如，阳光充足的栖息地的物种是否具有光合速率和叶子特征，这些特征往往会以相对牺牲相对成本为代价在明亮的环境中促进生长）阴凉处生长不良（对于阴凉栖息地的物种反之亦然），以及林下物种（栖息在不均匀且相对不可预测的光环境中）是否表现出更多的能力来改变其光合形式和生理机能以应对变化当与研究物种之间的进化关系信息相结合时，这些信息将告诉我们在入侵阴影栖息地的不同阶段发生了哪些变化，哪些特征似乎适应了阴影环境，以及哪些特征似乎受到不同群体的进化历史的限制。这项研究将使 PI 首次能够在历史框架内调查光合作用对阳光和阴影的适应的兴起。这些结果应该增加我们对植物光合作用性能的生态限制的理解，特别是对半边莲的栖息地要求的理解，其中许多物种已经变得相当稀有。