DISSERTATION RESEARCH: Evolution and Diversification of Epiphytic Ferns

论文研究：附生蕨类植物的进化和多样化

• 批准号: 0408077
• 负责人: Kathleen Pryer
• 金额: $ 1.2万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408077&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Evolution; Diversification; Epiphytic

Vascular epiphytes-vascular plants that reside on an aboveground plant surface but do not extract water or nutrients from the host plant or the ground-make an important contribution to global plant diversity, comprising more than 10% of the known vascular plant species. Epiphytism has evolved numerous times and in all major vascular plant lineages, but not all transitions to the epiphytic habit have resulted in comparable levels of diversity and the contribution of epiphytes varies from lineage to lineage. Within ferns, 31% of the species are epiphytes, and the epiphytic habit has clearly been of considerable importance in the evolutionary history of this group. Nonetheless, remarkably little is known about the evolution and diversification of epiphytic ferns and several critical questions remain unanswered. How many times has epiphytism evolved in ferns? What morphological and ecological transformations are associated with the transition to the epiphytic habit? When did epiphytism evolve and what abiotic or biotic events may have spurred the diversification of epiphytic ferns? This award to Kathleen Pryer and Eric Schuettpelz will be used to address these questions through ancestral character state reconstructions and divergence time estimates within an explicit phylogenetic framework. There are three primary objectives to this study: (1) resolve a global phylogeny for ferns to serve as a tool for addressing evolutionary and ecological questions; (2) reconstruct the evolutionary history of epiphytism within ferns and identify the morphological and ecological innovations associated with the transition to epiphytism; and (3) estimate the relative timing of epiphytic fern diversifications and assess how these may have been impacted by the establishment of angiosperm-dominated everwet tropical forests-a possible diversification trigger. This study will provide training for Eric Schuettpelz in systematic biology, make significant contributions toward a complete understanding of plant evolution, and help in elucidating the origins of a part of global biodiversity that is much neglected. The resulting phylogenetic tree will further resolve the relationships among fern lineages, will allow for improved classification, and will serve as a framework for future evolutionary and systematic studies. Insight into the evolutionary history of epiphytism in ferns will likely extrapolate to other plant lineages, and information concerning the relative timing of epiphytic fern diversifications could have a profound impact on future thoughts concerning the basis of tropical diversity. If the establishment of angiosperm-dominated forest canopies is shown to have been a likely trigger for the diversification of epiphytic ferns, then it is highly probable that these canopies also spurred the diversification of epiphytic angiosperms and bryophytes, as well as many other canopy and terrestrial forest inhabitants. Much, if not all, of the extraordinary biodiversity present in the tropics may have been generated directly as a result of angiosperm-dominated everwet tropical forest establishment, but the magnitude and extent of this possible impact has yet to be evaluated.

维管附生植物是指生长在地上部但不从寄主植物或地面吸取水分或养分的维管植物，它对全球植物多样性做出了重要贡献，占已知维管植物种类的10%以上。附生已经进化了无数次，并在所有主要的维管植物谱系，但并不是所有的过渡到附生的习惯，导致可比的多样性水平和附生植物的贡献各不相同的谱系。在蕨类植物中，31%的物种是附生植物，而附生习性在这一类群的进化史上显然具有相当重要的意义。尽管如此，对附生蕨类植物的进化和多样化知之甚少，一些关键问题仍然没有答案。蕨类植物的附生进化了多少次？什么形态学和生态学的转变与附生习性的转变有关？附生现象是何时演化出来的？什么样的非生物或生物事件可能刺激了附生蕨类植物的多样化？这个奖给凯瑟琳普赖尔和埃里克Schuettpelz将用于解决这些问题，通过祖先的性格状态重建和分歧时间估计在一个明确的系统发育框架。本研究有三个主要目的：（1）解决蕨类植物的全球性进化问题，作为解决进化和生态问题的工具：（2）重建蕨类植物内附生的进化历史，并确定与附生过渡相关的形态和生态创新;和（3）估计附生蕨类植物多样化的相对时间，并评估这些可能受到被子植物占主导地位的常绿热带森林的建立的影响-一个可能的多样化触发因素。这项研究将为Eric Schuettpelz提供系统生物学方面的培训，为全面了解植物进化做出重大贡献，并有助于阐明被忽视的全球生物多样性的起源。由此产生的系统发育树将进一步解决蕨类植物谱系之间的关系，将允许改进分类，并将作为未来的进化和系统研究的框架。深入了解蕨类植物中附生的进化历史可能会外推到其他植物谱系，关于附生蕨类植物多样化的相对时间的信息可能会对未来关于热带多样性基础的思想产生深远的影响。如果被子植物占主导地位的森林冠层的建立被证明是一个可能的触发器的附生蕨类植物的多样化，那么它是非常有可能的，这些冠层也刺激了附生被子植物和britonites，以及许多其他冠层和陆地森林居民的多样化。热带地区存在的许多（如果不是全部的话）非凡的生物多样性可能是被子植物占主导地位的常湿热带森林建立的直接结果，但这种可能影响的程度和范围尚未得到评估。