Dissertation Research: Phylogeny of Helianthus Including New Methods to Detect Reticulate Evolution

论文研究：向日葵的系统发育，包括检测网状进化的新方法

• 批准号: 0408012
• 负责人: C. Randal Linder
• 金额: $ 1.2万
• 依托单位: University of Texas at Austin
• 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 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408012&HistoricalAwards=false
• 关键词: Dissertation; Research; Phylogeny; Helianthus; Including

Project summary for general readers Despite the agronomic and research importance of the genus Helianthus (sunflowers), the evolutionary relationships among the species are still largely unresolved. In addition to H. annuus, the cultivated species of sunflower, the genus contains an additional 48 species that are distributed across North America. The annual species are a model system for studying diploid hybrid speciation - speciation caused by normal sexual hybridization between two species - so their relationships have been closely researched. But relationships among the rest of the species, especially the perennials, are not well understood. This lack of resolution is mostly due mostly to recent rapid speciation and hybrid speciation. Resolving these relationships along with testing the existing parental hypotheses of the perennial hybrid sunflowers will be addressed using (1) a comparatively faster evolving marker; (2) tools for reconstructing reticulate evolution (an evolutionary history that has evolved in a net-like fashion, due to hybridization, instead of a tree-like pattern); and (3) multiple nuclear markers. Currently the number of nuclear markers that are accessible for inferring phylogenetic history is very limited. Our goal at the end of this project is to provide the plant systematic community with a set of universal nuclear primers for plants. In conjunction with colleagues in The Department of Computer Sciences, a comparative analysis of two entire plant genomes (Oryza and Arabidopsis) has produced a series of primer pairs that are conserved between these genomes. Using these primer pairs 18 plants are being screened across a wide taxonomic sampling: six species in Helianthus, six in Phalaenopsis (an orchid), and six that span other flowering plant groups. Data collected from these markers will be used with the new algorithms for reconstructing reticulate evolution and together these methods will be tested on the known parentage of the annual hybrid sunflowers. If these methods correctly infer these relationships then they will be applied more broadly to the less-studied perennial sunflowers. Scientific significance: The advancements made by project will be key in the reconstruction of the Tree of Life, both locally and globally. The resolution of sunflowers completes one lineage on the Tree of Life, while these new methods and markers will focus more widely on the accurate construction of the tree. Although the markers being collected will be used specifically for methods under this project, the capability for their use in other flowering plants will be of tremendous benefit. Additionally, the computational efforts used in this research have resulted in a new collaboration between computer scientists and biologists that has greatly enhanced the creativity of future research questions. An immediate educational impact has also been felt: at present, five undergraduates have been trained in valuable molecular techniques that can be applied in their future research.

尽管向日葵属在农艺学和研究上具有重要意义，但其物种间的进化关系仍未得到解决。除了向日葵的栽培种H. annuus外，该属还包括另外48种分布在北美的向日葵。一年生物种是研究二倍体杂交物种形成的一个模式系统，因此它们之间的关系得到了密切的研究。但其他物种之间的关系，尤其是多年生植物之间的关系，还没有得到很好的理解。这种分辨率的缺乏主要是由于最近的快速物种形成和杂交物种形成。解决这些关系以及测试多年生杂交向日葵的现有亲本假设将使用(1)一个相对更快的进化标记；(2)重建网状进化的工具（由于杂交而以网状方式进化的进化史，而不是树状模式）；(3)多核标记物。目前，可用于推断系统发育历史的核标记数量非常有限。本项目的最终目标是为植物系统界提供一套通用的植物核引物。与计算机科学系的同事一起，对两个完整的植物基因组（水稻和拟南芥）进行了比较分析，产生了一系列在这些基因组之间保守的引物对。利用这些引物对，在广泛的分类样本中筛选了18种植物：向日葵属的6种，蝴蝶兰属的6种，以及跨越其他开花植物群的6种。从这些标记中收集的数据将与重建网状进化的新算法一起使用，这些方法将在已知的一年生杂交向日葵亲本上进行测试。如果这些方法正确地推断出这些关系，那么它们将更广泛地应用于研究较少的多年生向日葵。科学意义：项目取得的进展将是重建当地和全球生命之树的关键。向日葵的分辨率完成了生命之树的一个谱系，而这些新的方法和标记将更广泛地关注于生命之树的准确构建。虽然收集的标记将专门用于本项目下的方法，但将其用于其他开花植物的能力将带来巨大的好处。此外，在这项研究中使用的计算努力导致了计算机科学家和生物学家之间的新合作，这极大地增强了未来研究问题的创造力。在教育方面也产生了直接的影响：目前，五名本科生已经接受了有价值的分子技术的培训，这些技术可以应用于他们未来的研究。