Dissertation Research: Systematics of Stylocline (Asteraceae)

研究生Morefield在Rancho圣安娜植物园的Loren Rieseberg博士的指导下，正在研究美国西南部向日葵的几个物种，Stylocline及其亲属，以评估这些一年生和高度近亲繁殖植物种群内和种群之间的遗传和基因组变异水平。主要的分析方法包括蛋白质电泳以取样从植物中提取的可溶性酶的变化，沿着DNA分析方法以测量核核糖体基因和叶绿体基因中的突变差异。几个相关的植物类群也将进行研究，以构建一个系统发育框架，表明物种之间的进化关系。许多关于物种形成过程的理论讨论都依赖于从杂交生物中获得的知识，但许多植物群体中有很高比例的自我繁殖个体。目前还不清楚这些近亲繁殖群体是否遵循相同的进化规则，以及它们是否在当地种群中具有相似的遗传变异性。通过形态特征研究的额外数据，学生还将能够确定物种识别的可靠特征，绘制所有分类群的地理分布图，并评估所有具有可区分特征的群体的正确科学名称。因此，学生将在植物多样性分析中获得广泛的现代系统方法的宝贵培训。

Gradute student Morefield under the guidance of Dr. Loren Rieseberg of the Rancho Santa Ana Botanic Garden is studying the several species of an American Southwest sunflower relative, Stylocline, and its relatives, in order to assess levels of genetic and genomic variability within and among populations of these annual and highly inbreeding plants. Primary methods of analysis include protein electrophoresis to sample variation in soluble enzymes extracted from the plants, along with methods of DNA analysis to measure mutational differences in nuclear ribosomal genes and in chloroplast genes. Several related groups of plants also will be studied, in order to construct a phylogenetic framework indicating evolutionary relationships among the species. Much of the theoretical discussion about speciation processes relies upon knowledge acquired from organisms that cross-breed, but many groups of plants include high proportions of self-fertilizing individuals. It is unclear whether these inbreeding groups follow the same evolutionary rules, and whether they harbor similar amounts of genetic variability within local populations. With additional data from studies of morphological features, the student will also be able to determine reliable features for species identification, map geographic distributions for all the taxa, and evaluate the correct scientific names for all those groups with distinguishable characteristics. The student will thus gain valuable training in a broad range of modern systematic methods in the analysis of plant diversity.