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

小行星9706948 研究生杰森·布拉德福德在华盛顿大学的芭芭拉·沙尔博士和密苏里州植物园的保罗·贝瑞博士的指导下，正在研究热带树木属韦曼尼亚（Cunoniaceae）复杂花序结构的形态进化。在南美洲和马达加斯加的部分地区进行了广泛的实地采集，并在澳大拉西亚的物种多样性高的地区进行了额外的采集。研究的一个主要重点是核核糖体RNA基因的DNA测序，以产生适合于从物种间的突变差异构建属的系统发育框架的数据。在该属估计的150种物种中，约有三分之一将进行DNA变异分析。然后，将进行分支开花轴（花序）的位置和复杂性的研究，以区分可能是共同祖先的结果的结构与不同谱系中作为收敛适应而产生的结构。 在一个以热带木本植物为重点的项目中，布拉德福德先生将把分子和形态学方法引入分类学研究，他将在研究不足的美拉尼西亚和波利尼西亚地区增加实地收集，以在南半球范围内对Weinmannia多样性进行采样。分子系统发育数据将增强世界上几个实验室正在进行的双子叶植物系统发育的一般研究。形态学分析有助于重新研究模块化的生长模式在开花植物，在时间（异时性）和定位（异位）的差异特征相关物种的营养和生殖轴。

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.