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

林恩克拉克博士和豪尔赫G.桑切斯-肯在爱荷华州州立大学进行恐慌草（也称为Panicoid/Centothecoid分支）内部进化关系的研究。目前对草的多样性的认识主要有两大类：1）竹子、水稻和早熟禾; 2）稗草、铁线草、相思草和芦苇。 后一组包括大约一半的禾本科物种多样性（超过5,000种），包括几种主要作物和杂草，但这组内的关系仍然知之甚少，阻碍了对几个生物学重要特征进化的严格理解。本研究的目的是1）重建主要的进化关系内的恐慌草（一个谱系超过3,000种，包括高粱，玉米，甘蔗，和一些重要的杂草），和2）花的性别，淀粉粒，和叶解剖在这个组的进化解释。 将使用来自叶绿体和核基因的信息以及形态学数据，并将增加对知之甚少的Centothecoids及其盟友的采样。 初步研究了蜡质基因的变化及其对淀粉粒发育的影响。 更广泛的意义和科学的重要性，这个项目是，一个主要群体的草的进化历史和多样化的更好的理解将提供一个出发点，在生态学和保护，作物改良，杂草控制等领域的更广泛的研究，和分子生物学。 这一谱系的预测性分类也将产生，并将采取探索禾本科植物淀粉粒中基因表达的第一步。 一名来自代表性不足群体的研究生将接受现代系统学的高级培训。

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.