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首页> 外文学位 >Phylogeny, character evolution, and biogeography of Yucca L. (Agavaceae) as inferred from plant morphology and sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA.
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Phylogeny, character evolution, and biogeography of Yucca L. (Agavaceae) as inferred from plant morphology and sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA.

机译：从植物形态和核糖体DNA的内部转录间隔区（ITS）区域的序列推断，丝兰的生长史，特征演变和生物地理。

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摘要

The genus Yucca consists of 46 perennial species distributed primarily in the warm deserts of Mexico and the United States. Although there are several taxonomic treatments of yuccas, the phylogeny of the group is poorly known. It is unclear which taxa retain primitive characters and how characters have evolved. In addition, the relationships of taxa within the genus are uncertain. The goals of this research were to discern the phylogeny and patterns of speciation and character evolution within Yucca.; Morphological and molecular analyses were undertaken to provide systematic data for phylogenetic analysis. The Internal Transcribed spacer (ITS) region of the nuclear ribosomal DNA repeat was sequenced to determine levels of genetic variation between Yucca species and outgroup genera. Morphological variation was examined using characteristics of plant habit, leaf, inflorescence, fruit and pollen morphology. Using parsimony analysis, the data sets were analyzed and compared. The sequence of character changes was mapped onto the tree topology to evaluate patterns of character evolution over time. Geographic distributions of closely aligned species were mapped using the phylogenetic relationships shown in the tree topology. From these, patterns of speciation through time and across the North American continent were evaluated.; The traditional taxonomic treatment of the genus was compared to a phylogeny generated by molecular data. In the past, the genus has been divided into four sections based upon shared fruit, pistil and leaf characters. Section Hesperoyucca, with a unique, capitate stigma and dry fruit, contains species of the Yucca whipplei complex. Section Clistocarpa, with spongy fruit, contains a monotypic species, Y. brevifolia. Section Chaenocarpa contains 22 dry-fruited species and sect. Sarcocarpa contains 23 fleshy-fruited species. Results indicated that the fleshy-fruited species are a monophyletic lineage, but the dry-fruited species are not. The species of sect. Hesperoyucca were shown to be more closely allied to Hesperaloe than to Yucca, providing support for the placement of sect. Hesperoyucca outside of Yucca. The dry fruit of the species of ser. Rupicolae arose from the lineage which gave rise first to spongy fruit (Y. brevifolia). The rest of the dry-fruited species are monophyletic and arose shortly after the lineage bearing Y. brevifolia. A taxonomic revision is warranted that will reflect the naturalness of the group.; Biogeographic analysis indicates that the Mohave and Sonoran deserts contain the species of Yucca most basal to the lineage. Most of the species with sympatric distributions are not closely related, suggesting a repeated pattern of dispersal or vicariance, then allopatric speciation within lineages over time.
机译：丝兰属包括46个多年生物种，主要分布在墨西哥和美国的温暖沙漠中。尽管对丝兰有几种分类学治疗方法，但该类的系统发育学知之甚少。目前尚不清楚哪个分类单元保留原始字符以及字符如何演变。另外，属内的分类单元的关系是不确定的。这项研究的目的是辨别丝兰内物种的系统发育和模式以及性状进化。进行了形态学和分子分析，为系统发育分析提供了系统的数据。对核糖体DNA重复序列的内部转录间隔区（ITS）区域进行测序，以确定丝兰属和外群属之间的遗传变异水平。使用植物习性，叶片，花序，果实和花粉形态的特征检查形态变化。使用简约分析，对数据集进行分析和比较。角色更改的顺序映射到树形拓扑上，以评估角色随时间演变的模式。使用树形拓扑中显示的系统发育关系，可以对紧密排列的物种的地理分布进行映射。从中，评估了随着时间的推移以及整个北美大陆的物种形成模式。将该属的传统分类学处理与通过分子数据产生的系统发育进行了比较。过去，根据果实，雌蕊和叶的性状，该属被分为四个部分。 Hesperoyucca节具有独特的头状柱头和干果，其中包含丝兰Whipplei复合体。具有海绵状果实的Clistocarpa节含有单型种，短叶耶尔森氏菌。 Chaenocarpa节包含22种干果物种和教派。果树皮含有23种果肉种类。结果表明，果肉种类是单系谱系，而干果种类不是。宗派的种类。结果表明，与花丝兰相比，花丝叶猴与花丝兰更紧密地联系在一起，为该教派的安置提供了支持。 Hesperoyucca在丝兰之外。 ser种的干果。羽扇豆科起源于首先产生海绵状水果（Y. brevifolia）的血统。其余的干果种类是单系的，在带有短叶耶尔森氏菌的血统后不久就出现了。必须对分类进行修订，以反映该组的自然性。生物地理学分析表明，莫哈韦沙漠和索诺兰沙漠含有最古老的丝兰物种。大多数具有同族分布的物种之间没有密切的联系，这表明随着时间的推移，谱系或配种出现了重复的模式，然后沿袭了谱系内的异源物种。

著录项

  • 作者

    Clary, Karen Husum.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Biology Botany.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 214 p.
  • 总页数 214
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 植物学;
  • 关键词

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