Independently assessing seed-plant molecular phylogenies: does the cordaite fossil record support close relationships between Gnetales and conifers

独立评估种子植物分子系统发育：堇青石化石记录是否支持买麻藤目和针叶树之间的密切关系

• 批准号: NE/E004369/1
• 负责人: Jason Hilton
• 金额: $ 37.87万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE004369%2F1
• 关键词: Independently; assessing; seed; plant; molecular

The study of DNA in living organisms has revolutionised how we conceptualise and analyse the evolutionary history of biological groups, a scientific discipline known as phylogeny reconstruction. Earlier methods relied on the analysis of morphological and anatomical features of organisms in what are termed morphological cladistic analyses, but more recently these have been used only to supplement analyses based on DNA sequences, which are termed molecular cladistic analyses. In some cases the results gained from morphological and molecular analyses contrast strongly with each other, generating damaging uncertainties regarding which set of evidence more correctly infers the evolutionary history of the organisms studied, and undermining the confidence not only of formal classifications but also of any following evolutionary interpretations. One such critical group, the seed plants, originated ca. 363 million years ago in the late Devonian period; they have an extensive fossil record and dominate modern terrestrial ecosystems. Living seed plants represent five major taxonomic groups: cycads, Ginkgo, conifers, Gnetales and angiosperms (flowering plants). Several other major seed-plant groups evident in the fossil record are long extinct, and so cannot yield molecular information. They include a complex of plants that combine fern-like foliage and seeds, termed the pteridosperms, that are implicated in the evolutionary origins of all five extant groups of seed-plants. Such fossils are the only means of bridging the vast morphological gaps that separate the five extant seed-plants groups, which cannot be addressed directly using molecular systematic methods. Of the five extant groups, the Gnetales includes three distinct extant lineages (represented by the genera Welwitschia, Gnetum and Ephedra) that show remarkable combinations of morphological features. Most morphological cladistic studies place Gnetales next to angiosperms, immediately above fossil groups such as the advanced pteridosperm Pentoxylon and the Bennettitales (the Anthophyte hypothesis of seed-plant relationships). However, data-rich (if taxon-poor) molecular phylogenetic studies increasingly place Gnetales either at the base of the conifers (the Gnetifers hypothesis) or within conifers immediately adjacent to pines (the Gnepines hypothesis). This project seeks to (a) independently assess current molecular results with new fossil data from exceptionally well-preserved plants, and (b) integrate the results with morphological data from current investigations of development and the key genes that underpin development, together with molecular phylogenies. Thus, we aim to employ a whole-evidence approach to reconstruct the evolutionary history of seed plants. The Gnepine, Gnetifer and Anthophyte hypotheses of relationships will be tested by carefully targeted analysis of the fossil record, focusing on detailed morphological features that may, or may not, unite Gnetales with conifers. Recent morphological reanalysis of living Gnetales shows that phylogeneticists have previously been misinterpreting their male organs, which are similar to some extinct conifers and to a closely allied extinct group called the cordaitean coniferophytes. This will be the first detailed study designed to determine whether the cordaites have fundamental similarities with Gnetales. Any fundamental similarities will support the Gnepine and especially the Gnetifer hypotheses. Any fundamental dissimilarities may return the focus of gnetalean relationships to the angiosperms inherent in the Anthophyte hypothesis, but may also require substantial revision of inferred relationships among major groups within the coniferophytes. We are therefore confident that this project will help to elucidate the controversial history of seed plants.

对活生物体DNA的研究已经彻底改变了我们如何概念化和分析生物群体的进化史，这是一门被称为系统发育重建的科学学科。早期的方法依赖于被称为形态分支分析的生物形态和解剖特征的分析，但最近这些方法仅用于补充基于DNA序列的分析，这被称为分子分支分析。在某些情况下，从形态学和分子分析中获得的结果彼此之间有强烈的反差，在哪一组证据更正确地推断所研究生物的进化史方面产生了破坏性的不确定性，不仅破坏了正式分类的信心，也破坏了随后任何进化解释的信心。其中一个关键的群体，种子植物，起源于大约3.63亿年前的泥盆纪晚期；它们有广泛的化石记录，主宰着现代陆地生态系统。活着的种子植物分为五大类：苏铁、银杏、针叶树、片麻科和被子植物（开花植物）。化石记录中其他几个主要的种子植物群早已灭绝，因此无法提供分子信息。它们包括一种将蕨类植物的叶子和种子结合在一起的植物复合体，被称为翼类植物，它与现存的五种种子植物的进化起源有关。这样的化石是唯一的手段，弥合巨大的形态差距，将五个现存的种子植物群分开，这不能直接用分子系统的方法来解决。在现存的五个类群中，麻属包括三个不同的现存谱系（以威氏属、麻属和麻黄属为代表），它们表现出显著的形态特征组合。大多数形态学分支学研究将片麻类植物放在被子植物旁边，紧靠化石类群，如先进的蕨类植物penttoxylon和Bennettitales（种子植物关系的花药假说）。然而，数据丰富（如果分类单元贫乏）的分子系统发育研究越来越多地将片麻属植物置于针叶树的基部（片麻属假说）或紧挨着松树的针叶树中（片麻属假说）。该项目旨在(a)利用保存特别完好的植物的新化石数据独立评估当前的分子结果，(b)将结果与当前发育研究的形态学数据、支撑发育的关键基因以及分子系统发育结合起来。因此，我们的目标是采用全证据的方法来重建种子植物的进化史。我们将通过对化石记录的仔细分析，重点关注可能（也可能不）将片麻属植物与针叶树结合起来的详细形态学特征，对片麻属、片麻属和花药植物之间关系的假说进行检验。最近对现存针叶树的形态学重新分析表明，系统发育学家此前一直错误地解读了它们的雄性器官，它们与一些已灭绝的针叶树和一种密切相关的已灭绝的针叶树类群相似。这将是第一个详细的研究，旨在确定心球虫是否与蛛丝有基本的相似之处。任何基本的相似性都将支持Gnepine假说，尤其是Gnetifer假说。任何根本的差异都可能将类目关系的焦点回归到花药假说中固有的被子植物上，但也可能需要对针叶植物中主要类群之间的推断关系进行实质性的修正。因此，我们相信这个项目将有助于阐明种子植物有争议的历史。

项目成果

Computational phylogenetics and molecular systematics.

计算系统发育学和分子系统学。

• 发表时间: 2007
• 作者: Bateman, R. M., Hilton, J. & Rudall, P. J.

Reinvestigation of the Enigmatic Carboniferous Sphenophyte Strobilus Cheirostrobus Scott and Implications of In Situ Retusotriletes Spores

神秘的石炭纪蝶藻 Strobilus Cheirostrobus Scott 的重新研究及其原位 Retusotriletes 孢子的意义

• DOI: 10.1086/704945
• 发表时间: 2019
• 期刊: International Journal of Plant Sciences
• 影响因子: 2.3
• 作者: Neregato R

Climate Change, Ecology and Systematics

气候变化、生态学和系统学

• DOI: 10.1017/cbo9780511974540.004
• 发表时间: 2011
• 作者: Bateman R

Pollen cones and associated leaves from the Lower Cretaceous of China and a re-evaluation of Mesozoic male cycad cones

• DOI: 10.1080/14772019.2013.819817
• 发表时间: 2014-09
• 期刊: Journal of Systematic Palaeontology
• 影响因子: 2.6
• 作者: S. Deng;J. Hilton;I. Glasspool;J. Dejax

Taxonomy and climate change

分类学和气候变化

• 发表时间: 2008
• 作者: Bateman, R. M.