Dissertation Research: Heterochrony in the Dry Tropics: Moringa

9801128瑞文/沙尔/奥尔森 辣木是辣根树科（辣木科）中唯一的一个属，其形态和地理范围都是无与伦比的，从马达加斯加和纳米比亚的巨大蓄水“瓶树”，到阿拉伯和印度的细长树木，再到非洲东北部的微小块茎草本植物。 植物形态的最高多样性被认为发生在干燥的热带地区，但产生这种多样性的机制却很少被研究。 在这篇博士论文的研究中，彼得乌鸦，芭芭拉Schaal和博士生马克奥尔森将研究历史变化的作用，在时间的发展事件（“异时性”）中产生的阵列形状之间的物种辣木。 这项研究将采用一种新的技术组合来跟踪木材和花卉的发展，无论是在野生植物还是在精心控制的栽培条件下。 发育研究将在不同辣木物种的历史（“系统发育”）关系的假设背景下进行解释，研究人员将从形态和分子（基因序列）特征的分析中推断。 这项研究应该有助于了解具有最近共同历史的植物如何在形式和功能上多样化，以便在不同的环境条件下茁壮成长。 该奖项包括国际项目司非洲、近东和南亚项目的贡献。

9801128 Raven/Schaal/Olsen Moringa, the only genus of the horseradish tree family (Moringaceae), spans an unparalled range of form and geography, from massive, water-storing "bottle trees" in Madagascar and Namibia, to slender trees in Arabia and India, to tiny tuberous herbs in northeastern Africa. The highest diversity of plant form is thought to occur in the dry tropics, but the mechanisms that have produced this diversity is little studied. In this doctoral dissertation research, Peter Raven, Barbara Schaal and doctoral student Mark Olsen will examine the role of historical changes in the timing of developmental events ("heterochrony") in producing the array of shapes among species of Moringa. The research will employ a novel combination of techniques to follow the development of wood and flowers, both in wild plants and in those maintained under carefully controlled conditions of cultivation. The developmental studies will be interpreted in the context of an hypothesis of the historical ("phylogenetic") relationships of the different Moringa species that the researchers will infer from an analysis of morphological and molecular (gene sequence) characters. The research should contribute to an understanding of how plants with recent common histories may diversify in form and function to thrive in different environmental conditions. This award includes a contribution from the Africa, Near East and South Asia program, Division of International Programs.