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

Sytsma和Pires 9902169综合了生物系统学(对生物变异、多样性和多样性的生物学方面的实验研究)和系统学(研究生物的系谱关系)，一直是进化和生态研究的有前途的途径，因为系谱为进行生物学比较提供了有意义的历史背景。Themidaceae是北美西部的一种新近复活的洋葱状草本植物家族。该科是一个理想的模式系统，因为几个属(例如，龙须草属)在花特征、染色体数量和栖息地偏好方面具有令人难以置信的多样性。多倍体--当一个生物体包含两组或更多组染色体--似乎很常见，而且相当数量的物种是仅在加利福尼亚州岛屿、蛇纹石土壤或其他不寻常的底物上发现的特有物种。谱系历史将使用分子和形态数据来得出。这一历史背景将与新的染色体绘制技术相结合，以确定多倍体的类型以及涉及物种形成和家族特有的各种染色体变化。染色体涂色还可以帮助确定哪些DNA序列应该在系谱研究中进行比较。初步的研究结果已经在不同的分类水平上揭示了决明科植物在形态、细胞学和生态学方面的新见解。

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.