Dissertation Research: Molecular Systematics and Evolution in Mimulus and Tribe Mimuleae

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Systematists are charged with the difficult tasks of quantifying and characterizing diversity in large groups of organisms and of identifying discontinuities in morphological or genetic diversity that correspond with species delimitations. These tasks are especially critical for groups that have, 1) species that have become model systems for studying evolution and ecology, and 2) a large number of rare or threatened species. Species in the plant genus Mimulus have become model systems for the study of evolutionary processes in nature due to the diversity of interesting traits and adaptations in the genus. Species in this worldwide genus have different chromosome numbers, reproductive strategies, and pollinators, and interesting adaptations to extreme environments. Many species of Mimulus are also rare. Phylogenetic estimates of widely distributed, species-rich groups are important, because they give biologists the opportunity to study broad-scale diversification events, in which parallel radiations into spatially separated, similar environments may have occurred. An estimate of the evolutionary relationships among the species is useful in documenting these radiations and enables comparative analyses. The role of systematists in delimiting species is equally vital. Conservation plans and studies of evolutionary processes require accurate circumscription of species. The purposes of this project are: 1) to determine the relationship of Mimulus to other genera, 2) to determine whether Mimulus is a natural group, 3) to estimate species-level relationships and define taxonomic units within Mimulus and 4) to explore evolutionary patterns in the newly recognized radiation of Mimulus in Australia. The proposed research will accomplish two goals. We will use DNA sequence information from two different genomes to further develop species-level phylogenetic hypotheses in the newly recognized Australian Mimulus clade. These analyses will provide an appropriate global perspective on diversification in the newly circumscribed family Phrymaceae. These will also provide an explicit phylogenetic framework for evaluating morphological changes in this group and will serve as a basis for future comparative studies. We will use DNA sequence and polymorphic DNA fragments to analyze patterns of genetic diversification in Mimulus sect. Eunanus. These patterns will be used to guide taxon delimitation and will serve as a model for defining taxa in groups with few morphological character differences. Because many of its species are rare, accurate species delimitation in Mimulus is critical to establishing appropriate management policies.