Dissertation Research: Molecular Systematics and Evolution in Mimulus and Tribe Mimuleae

系统学家承担着艰巨的任务：量化和描述大型生物群体的多样性，识别与物种划分相对应的形态或遗传多样性的不连续性。这些任务对于以下群体尤其重要：1)物种已经成为研究进化和生态学的模型系统；2)大量稀有或濒危物种。拟态植物属的物种由于其有趣的特征和适应性的多样性而成为研究自然界进化过程的模式系统。这个世界范围内的物种有不同的染色体数目、繁殖策略和传粉者，以及对极端环境的有趣适应。许多种类的含羞草也很罕见。对分布广泛、物种丰富的种群进行系统发育估计是很重要的，因为它们使生物学家有机会研究大范围的多样化事件，在这些事件中，平行辐射可能发生在空间分离的类似环境中。估计物种之间的进化关系有助于记录这些辐射并进行比较分析。系统学家在划分物种方面的作用同样至关重要。保护计划和进化过程的研究需要对物种进行精确的界定。本项目的目的是：1)确定Mimulus与其他属的关系；2)确定Mimulus是否是一个自然类群；3)估计Mimulus的物种水平关系并定义其分类单位；4)探索新发现的Mimulus在澳大利亚的辐射的进化模式。拟议的研究将实现两个目标。我们将使用来自两个不同基因组的DNA序列信息来进一步发展新认识的澳大利亚模拟枝的物种水平的系统发育假设。这些分析将为新限定的蕨科的多样化提供一个适当的全球视角。这些也将为评估这一群体的形态变化提供一个明确的系统发育框架，并将作为未来比较研究的基础。我们将利用DNA序列和多态DNA片段分析拟南芥的遗传多样化模式。这些模式将用于指导分类单元的划分，并将作为在形态特征差异较小的类群中定义分类单元的模型。由于其许多物种是罕见的，准确的物种划分是建立适当的管理政策的关键。

Systematists are charged with the difficult tasks of quantifying and characterizing diversity in large groups of organisms and of identifying discontinuities in morphological or genetic diversity that correspond with species delimitations. These tasks are especially critical for groups that have, 1) species that have become model systems for studying evolution and ecology, and 2) a large number of rare or threatened species. Species in the plant genus Mimulus have become model systems for the study of evolutionary processes in nature due to the diversity of interesting traits and adaptations in the genus. Species in this worldwide genus have different chromosome numbers, reproductive strategies, and pollinators, and interesting adaptations to extreme environments. Many species of Mimulus are also rare. Phylogenetic estimates of widely distributed, species-rich groups are important, because they give biologists the opportunity to study broad-scale diversification events, in which parallel radiations into spatially separated, similar environments may have occurred. An estimate of the evolutionary relationships among the species is useful in documenting these radiations and enables comparative analyses. The role of systematists in delimiting species is equally vital. Conservation plans and studies of evolutionary processes require accurate circumscription of species. The purposes of this project are: 1) to determine the relationship of Mimulus to other genera, 2) to determine whether Mimulus is a natural group, 3) to estimate species-level relationships and define taxonomic units within Mimulus and 4) to explore evolutionary patterns in the newly recognized radiation of Mimulus in Australia. The proposed research will accomplish two goals. We will use DNA sequence information from two different genomes to further develop species-level phylogenetic hypotheses in the newly recognized Australian Mimulus clade. These analyses will provide an appropriate global perspective on diversification in the newly circumscribed family Phrymaceae. These will also provide an explicit phylogenetic framework for evaluating morphological changes in this group and will serve as a basis for future comparative studies. We will use DNA sequence and polymorphic DNA fragments to analyze patterns of genetic diversification in Mimulus sect. Eunanus. These patterns will be used to guide taxon delimitation and will serve as a model for defining taxa in groups with few morphological character differences. Because many of its species are rare, accurate species delimitation in Mimulus is critical to establishing appropriate management policies.