Dissertation Research: Integrating Biosystematics and Phylogenetics: Floral Diversity, Polyploidy, and Serpentine Endemism in the Recently Resurrected Plant Family Themidaceae

Sytsma和Pires 9902169整合生物系统学（生物变异，多样性和多样化的生物学方面的实验研究）和遗传学（生物体的系谱关系的研究）已经成为进化和生态学研究的一个有前途的途径，因为系谱为生物学比较提供了有意义的历史背景。 Themidaceae是一个最近复活的植物科洋葱状草本植物，产于北美西部。 科是一个理想的模式系统，因为几个属（例如，Brodiaea）在花的特征、染色体数目和栖息地偏好方面具有令人难以置信的多样性。 当一个生物体含有两套或多套染色体时，多倍体就显得很常见，而且有相当数量的物种是仅在加州岛屿、蛇纹岩土壤或其他不寻常的基质上发现的特有种。 系谱历史将使用分子和形态学数据。 这一历史背景将与新的染色体绘画技术相结合，以确定多倍体的类型和染色体变化的种类，这些变化与该科的物种形成和特有性有关。 染色体彩绘还可以帮助确定哪些DNA序列应该用于系谱学研究。 初步结果已经揭示了新的形态学，细胞学和生态学的见解在不同的分类水平内的Themidaceae。

Sytsma and Pires 9902169Integrating biosystematics (the experimental study of biological aspects of organismal variation, diversity and diversification) and phylogenetics (the study of genealogical relationships of organisms) has been a promising avenue for evolutionary and ecological investigations because genealogies provide a meaningful historical context for making biological comparisons. Themidaceae is a recently resurrected plant family of onion-like herbs from western North America. The family is an ideal model system because several genera (e.g., Brodiaea) are incredibly diverse with respect to floral features, chromosome number, and habitat preference. Polyploidy - when an organism contains two or more sets of chromosomes -appears common, and a significant number of species are endemics found only on California islands, serpentine soils, or other unusual substrates. Genealogical histories will be derived using both molecular and morphological data. This historical context will be integrated with newchromosome painting techniques to determine the types of polyploidy andkinds of chromosomal change involved in speciation and endemism within thefamily. Chromosome painting can also assist in determining which DNAsequences should be compared for genealogical studies. Preliminary resultshave already revealed new morphological, cytological, and ecological insights at various taxonomic levels within the Themidaceae.