Dissertation Research: Evolutionary Diversification of Encelia Based on Multiple DNA Sequences

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This doctoral dissertation research project examines geographic patterns of genetic variation in a group of Sonoran and Mojave Desert plants in order to address two objectives. The first objective is to assess genetic relationships among three genera of the sunflower family in order to discern if speciation is correlated with geographic isolation, resulting from the formation of the Gulf of California. The second objective is to assess genetic relationships among populations of brittlebush, one widespread member of the genus Encelia, in order to understand how plant populations in these deserts were affected by climate change during the last glacial period. A phylogeographic approach, which makes use of DNA sequences, will be used. This approach first estimates relationships within and among species, and then examines these relationships in the context of the geologic and geographic history of the species.This research is significant for two reasons. First, these data will be important for understanding how glaciation, geographical isolation, colonization, range expansion, fluctuations in population size, and gene flow influence genetic structure in plant populations. Second, very few studies have examined genetic structure and phylogeography in plant species of the Sonoran and Mojave Deserts. Furthermore, the approach proposed here is entirely novel for species in this area and is an important approach to develop and advance in the field of plant evolutionary genetics. This project will also provide important training to a female graduate student and, thus, will contribute to the advancement of women in science.