Drs. Nepokroeff and Wallace at the University of South Dakota plan to examine both phylogenetic and phylogeographic ("genealogical") relationships in the endemic Hawaiian plant genus Schiedea. Schiedea represents an excellent model system for examining species diversification on islands as the genus comprises one of the largest radiations of plant species (30 or so species) from a single presumed ancestor, and is one of the most diverse in terms of growth form, breeding systems, and habitat preferences. Studies of the ecology of pollination systems in Schiedea have become classic examples of major evolutionary transitions on islands. The Schiedea lineage is particularly interesting because it contains many species which exhibit floral dimorphism (separate male and female plants), the norm in humans and most animals, but rare in flowering plants. However, relationships among species of Schiedea, and thus number and order of transitions to floral dimorphism remain poorly resolved. The investigators plan to examine relationships among the 33 extant species of Schiedea using six DNA markers from several nuclear and plastid-genome sources. Additionally, the investigators plan to examine intraspecific genealogies by sampling populations of several closely related members of the lineage and analyzing these relationships within a coalescent framework, a newly described method for examining the history of genes within populations. The approach used by the investigators will allow for increased, if not complete, phylogenetic and genealogical resolution among species of Schiedea. Moreover, the approach used will enable the investigators to assess a number of microevolutionary processes, such as interspecific gene flow and hybridization, that may have contributed to species diversification and evolution of floral dimorphism. Because plant phylogeography is less well-studied than that of animals, this study will contribute to the developing field of plant phylogeography. The project will involve training for one female postdoctoral associate in the emerging field of statistical phylogeography. Opportunity for undergraduate involvement will be provided for ten students, who will receive training in laboratory skills, data analysis, research presentation and manuscript preparation. The University of South Dakota serves a predominantly rural community, with many first-generation college students and a high proportion of American Indian students, including one current Honors Biology major who will be pursuing independent research on Schiedea. In furtherance of these research and educational goals, co-funding from the NSF program for EPSCoR helps support this project. Lastly, over half of the 33 species in the Schiedea lineage are federally endangered or rare and several have already gone extinct in the wild; indeed Schiedea may contain more highly threatened plant species that any other lineage in Hawaii. These studies will result in development of publicly available, online graphical habitat-suitability models of 14 endangered species of Schiedea, linked to several existing websites of the Hawaiian flora. In addition to synthesizing genetic information with landscape level information, such models have the potential to be used in recovery plans by state agencies, and will provide additional training to undergraduates in landscape modeling.
