PRF/J: Intraspecific Chloroplast-DNA Variation and Phytogeography in the Pacific Northwest

许多植物表现出类似的地理分布，分布在阿拉斯加东南部到加利福尼亚州北部。对三个物种的分子遗传学研究表明，位于威斯康星州冰川最大值南部的细胞质存在明显的南北不连续。这些数据表明，冰川作用可能是造成这种不连续的原因之一，并提出了植物地理与太平洋西北部植物遗传结构之间存在联系的可能性。如果是这样，那么其他表现出相似地理分布的植物也应该表现出类似的遗传变异模式。这项研究解决了两个问题：(A)太平洋西北部植物类群的叶绿体DNA(CpDNA)变异是否存在相似的地理模式？(B)细胞质和核标记的变异模式是否一致？利用cpDNA限制性内切酶分析、rDNA分析和酶电泳法，对具有不同生活史特征的五个不同分类群(裸子植物、单子叶植物和双子叶植物)进行了研究。根据这些数据，将生成系统发育图，并将评估遗传变异模式。进一步的分析将解决生物地理问题，并可能有助于澄清疑似冰川避难所的位置和范围。%通过这次调查，我们对种内cpDNA变异程度的了解将得到加强。它还将有助于将物种内cpDNA变异的模式和程度与观察到的核遗传标记进行广泛比较，增进对植物遗传结构的了解，并在系统学和种群遗传学领域之间建立重要的联系。

Many plants exhibit a similar geographic distribution, occurring from southeastern Alaska to northern California. Molecular genetic investigations of three species have revealed a pronounced north-south cytoplasmic discontinuity located south of the Wisconsin glacial maximum. These data implicate glaciation as a possible causal factor in creating the discontinuity and raises the possibility of a link between phytogeography and the genetic architecture of plants in the Pacific Northwest. If so, then other plants displaying similar geographic distributions should also exhibit similar patterns of genetic variation. This study addresses two questions: (a) do similar geographic patterns of chloroplast DNA (cpDNA) variation occur throughout a spectrum of Pacific Northwest plant taxa?, (b) are patterns of variation in cytoplasmic and nuclear markers congruent? Populations of five taxonomically diverse taxa (a gymnosperm, a monocot, and dicots from Dilleniidae, Rosidae, and Asteridae) having different life history features will be examined using cpDNA restriction site analysis, rDNA analysis, and enzyme electrophoresis. From these data, phylogenies will be generated and patterns of genetic variation will be assessed. Further analysis will address biogeographical questions and may help clarify the location and extent of suspected glacial refugia. %%% Our knowledge of the extent of intraspecific cpDNA variation will be enhanced through this investigation. It will also serve to facilitate a broad comparison of patterns and extent of cpDNA variation within species to that observed for nuclear genetic markers, improve knowledge of plant genetic architecture, and establish an important link between the areas of systematics and population genetics.