DISSERTATION RESEARCH: Evolution and Systematics of Claytonia lanceolata sensu lato (Montiaceae)

Rancho Santa Ana Botanic Garden, Claremont CA

Investigators

Abstract

Polyploidization (whole genome duplication) is, and likely was, instrumental in the diversification of flowering plants. Understanding how and why polyploidy occurs in flowering plants may provide critical insight into the interplay of adaptation and historic environmental changes like glaciation, volcanism, and global climate change. This research will provide an improved understanding of diversification in the Claytonia lanceolata species complex, which is critical for effective conservation and management of the habitats in which they grow. Cutting edge biochemical and computational techniques now allow us to better estimate evolutionary histories, and test hypotheses concerning the ecological, temporal, and geographic context of speciation. This research will increase our understanding of gene dispersal via seeds and pollen, gene sharing among species, and the influence of chromosome number variation on plant diversification. A better understanding of relict alpine communities in California will be an additional, important contribution. Scientific communication, public outreach and mentoring undergraduate students are integral parts of the project as well. Polyploidy, potentially giving rise to species complexes, represents one of the fundamental processes in diversification and polyploids are important elements of plant communities across the globe. Preliminary study indicates that the Claytonia lanceolata species complex (Montiaceae), as currently circumscribed, is non-monophyletic and consists of many polyploid lineages inhabiting a variety of unique spatial and ecological conditions in the mountains of western North America. This project involves research into biogeography, chromosome evolution, niche diversification, and phylogeny of the C. lanceolata species complex and close relatives. The project investigates (1) abiotic and biotic habitat characteristics in the field to better understand mechanisms responsible for reproductive isolation, (2) chromosome number within and among populations using flow cytometry and chromosome counting methods to characterize potentially adaptive variation, (3) variation in vegetative characters using morphometrics to better develop hypotheses concerning selection acting on leaf and subterranean stem anatomy and morphology, and (4) patterns of inter-specific gene flow in sympatric populations using Next Generation Sequencing (RADseq) to understand the extent to which species are reproductively isolated. This research will result in a significant revision of our knowledge of species boundaries and their distributions in the C. lanceolata complex, in addition to the description of several taxa new to science.