DOCTORAL DISSERTATION: Phylogeny and Character Evolution in the Panicoid/centothecoid Clade (Poaceae)

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A grant has been awarded to Dr. Lynn Clark and Mr. Jorge G. Sanchez-Ken at Iowa State University to conduct research on evolutionary relationships within the panic grasses (also called the Panicoid/Centothecoid clade). Current knowledge of grass diversity shows two major groups: 1) the bamboos, rices, and bluegrasses, and 2) the panic grasses, wiregrasses, lovegrasses and reeds. The latter group comprises about half the species diversity of the grass family (over 5,000 species), including several major crops and weeds, yet relationships within this group are still poorly understood, hampering a rigorous understanding of the evolution of several biologically significant features. The objectives of this study are 1) reconstruction of major evolutionary relationships within the panic grasses (a lineage of over 3,000 species including sorghum, maize, sugarcane, and some important weeds), and 2) the evolutionary interpretation of flower sexuality, starch grains, and leaf anatomy within this group. Information from chloroplast and nuclear genes, as well as morphological data, will be used, and sampling of the poorly understood Centothecoids and allies will be increased. A preliminary study of changes in the waxy gene and its effects on the development of the starch grains will be included. The broader significance and scientific importance of this project are that an improved understanding of the evolutionary history and diversification of a major group of grasses will provide a point of departure for broader research in fields such as ecology and conservation, crop improvement, weed control, and molecular biology. A predictive classification for this lineage will also result, and the first steps in exploring gene expression in starch grains in grasses will be taken. A graduate student from an underrepresented group will be provided with advanced training in modern systematics.