DISSERTATION RESEARCH: Drought Tolerance and Evolution of Hydraulic Traits in Juniperus Species

论文研究：杜松属植物耐旱性与水力性状的进化。罗伯特B。杰克逊和Cynthia J. Willson杜克大学本研究将阐明系统发育和环境影响对杜松属（柏科）（一种耐旱的灌木和乔木属）的抗空化性和其他水力性状的影响。 实施的方法是一个独特的组合系统学和生理学和形态学的测量。 一个遍布美国的杜松物种的进化史。S.和加勒比海将构建基于DNA序列变异。 生理测量将包括抗空化和水力传导性的水力特性。 形态测量将包括木质部导管直径和木材密度。 将评估气候、土壤类型、物种和演替对水力性状变化的影响。 这项研究将是独特的，在其整合系统学，生理学和生态学解释模式的物种分布在进化的背景下。 探索环境和系统发育历史对物种内和物种间水关系变化的影响，将有助于更好地理解适应性性状进化和决定植物分布的重要因素。 这项研究将在生理生态学和植物系统学之间建立新的联系。 它还将使土地管理者深入了解对入侵北美灌木丛和草原的本土树种分布的控制。

Dissertation Research:Drought tolerance and evolution of hydraulic traits in Juniperus species.Robert B. Jackson and Cynthia J. WillsonDuke UniversityThis study will elucidate the effects of phylogenetic and environmental influences on cavitation resistance and other hydraulic traits in Juniperus (Cupressaceae), a drought-tolerant genus of shrubs and trees. The approach implemented is a unique combination of systematics and physiological and morphological measurements. A phylogeny for juniper species throughout the U. S. and Caribbean will be constructed based on DNA sequence variation. Physiological measurements will include the hydraulic traits of cavitation resistance and hydraulic conductivity. Morphological measurements will include xylem conduit diameter and wood density. The effects of climate, soil type, species, and phylogeny on the variation in hydraulic traits will be assessed. This study will be unique in its integration of systematics, physiology, and ecology to explain patterns of species distribution in an evolutionary context. Exploring the effects of environment and phylogenetic history on variation within and between species in water relations will provide a better understanding of adaptive trait evolution and the factors important in determining plant distributions. This study will forge new links between the disciplines of physiological ecology and plant systematics. It will also lend land managers insight into controls on distribution of native tree species invading into shrublands and grasslands in North America.