Dissertation Research: Morphological Diversification and Phylogentic Systematics of the Plant Genus Weinmannia

研究生Jason Bradford，在华盛顿大学的Barbara Schaal博士和密苏里植物园的Paul Berry博士的指导下，正在研究一种热带树属（Cunoniaceae）的Weinmannia的复杂花序结构的形态进化。在南美洲部分地区和马达加斯加进行了广泛的实地收集，并以澳大拉西亚物种多样性高的地区为目标进行了额外的收集。研究的一个主要重点是核糖体RNA基因的DNA测序，从物种之间的突变差异中产生适合构建属系统发育框架的数据。在估计的150个物种中，大约有三分之一的物种需要进行DNA变异分析。然后，将对分枝开花轴（花序）的位置和复杂性进行研究，以区分可能是共同祖先的结果的结构，以及在不同谱系中作为趋同适应而产生的结构。在一个以热带木本植物为重点的项目中，布拉德福德将把分子和形态学方法结合到分类学研究中，他还将在美拉尼西亚和波利尼西亚研究不足的地区进行实地采集，以取样整个南半球维曼尼亚的多样性。分子系统发育数据将增强正在世界上几个实验室进行的双科系统发育的一般研究。形态学分析有助于重新研究开花植物的模块化生长模式，其中时间（异时性）和定位（异位）的差异是相关物种营养轴和生殖轴的特征。

9706948 Schaal Graduate student Jason Bradford, under the direction of advisors Dr. Barbara Schaal at Washington University and Dr. Paul Berry at the Missouri Botanical Garden, is studying morphological evolution of the complex inflorescence structures in the tropical tree genus Weinmannia, of the Cunoniaceae family. Extensive field collecting has been done in parts of South America and in Madagascar, and additional collecting targets regions of high species diversity in Australasia. A major focus of the research is DNA sequencing of a nuclear ribosomal RNA gene, to generate data appropriate for constructing a phylogenetic framework of the genus from mutational differences among the species. About one-third of the estimated 150 species in the genus are to be analyzed for DNA variation. Studies of the position and complexity of the branched flowering axes, the inflorescences, will then be conducted, to distinguish structures that are likely the result of shared ancestry from those arising as convergent adaptations in different lineages. In a project focused on tropical woody plants, and bringing both molecular and morphological approaches to taxonomic study, Mr. Bradford will add field collecting in poorly researched areas of Melanesia and Polynesia to sample Weinmannia diversity across its southern-hemisphere range. The molecular phylogenetic data will augment general studies of dicot phylogeny ongoing in several laboratories in the world. The morphological analyses contribute to renewed study of modular growth patterns in flowering plants, where differences in timing (heterochrony) and in positioning (heterotopy) characterize vegetative and reproductive axes in related species.