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

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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.