Phylogeny of Malvatheca (Malvaceae) and the Pace and Place of Its Evolution

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0416096Baum Malvatheca is a group of about 2000 plant species that includes several economically important species (cotton, okra, kenaf, and balsa), united phylogenetically from the traditionally recognized cotton (Malvaceae), cocoa (Sterculiaceae), balsa (Bombacaceae), and linden (Tiliaceae) families on the basis of DNA sequence evidence. Most Malvatheca (more than 1700 species) are members of a group called the Eumalvoideae, which are primarily herbs and shrubs with a worldwide distribution. Prior work by Dr. David Baum and his colleagues suggested that the ancestors of Eumalvoideae were mangroves and coastal treelets that grew in Australasia; but only a handful of living species, the "Australasian grade," have retained this habit and distribution. The previous work also showed that the Australasian grade is likely descended from a group of Central and South American trees, the "Bombacaceous grade." The Eumalvoideae differs from the Australasian and Bombacaceous grade in the number of species it contains and in its extremely rapid molecular evolution (estimated at more than nine-fold that of the Bombacaceous grade). The proposed research, with colleagues Randy Small and Patrick Moss, aims (1) to use DNA sequences of plastid genes and the nuclear gene GBSSI to estimate when the Australasian grade arose, when and where the Eumalvoideae arose, and to shed light on the molecular mechanisms that may have led to accelerated molecular evolution and enhanced species diversification of Eumalvoideae; and (2) to use sequences of both plastid and nuclear DNA data to estimate the phylogenetic relationships within three important groups. These are (2a) Bombacoideae, a group that includes many large trees with spectacular flowers that grow in South and Central America as well as some African and Asian groups (e.g., the baobabs). The study will shed light on how the latter dispersed to Africa/Asia and will also clarify patterns of floral evolution. (2b) Matisieae, a group that includes ecologically significant understory trees from Central and South America. The study will shed light on the group's flower and fruit evolution. (2c) Malagasy Hibisceae, a group of putative relatives of Hibiscus that occur only in Madagascar. The study will resolve their phylogenetic relationships, which remain almost completely unknown, and will clarify when and from whence they arrived in Madagascar.During the funding period the PI will continue teaching a workshop for K-12 teachers on phylogenies ("tree thinking") and will develop new curricular materials for this purpose. He will recruit undergraduate researchers through the University of Wisconsin Undergraduate Research Scholars program, which has a high proportion of minority/financial aid students. Additionally, the researchers will teach a course on modern methods in Madagascar and continue to maintain the Malvaceae pages at the popular Tree of Life website.