MtDNA and cpDNA Phylogeographies of Ponderosa Pine and Limber Pine

本研究的目的是研究黄松和软松遗传变异的地理格局，目的是了解这些地理格局是如何形成的。这项研究利用了松树独特的遗传模式。线粒体DNA（mtDNA）是母系遗传的，在种子中仅短距离分散。叶绿体DNA（cpDNA）是父系遗传的，并且具有在风生花粉中传播很远距离的潜力。线粒体DNA的最小基因流使其能够检测冰川避难所之间进化的遗传差异。 cpDNA的高基因流使其能够衡量种群间的基因流程度。线粒体DNA和叶绿体DNA的序列变异将被用来描述两个物种范围内的变异。生物学家已经研究了几个世纪的植物和动物的地理变异，但分子技术的进步大大增加了可以从自然种群中收集的信息，数据处理的进步也大大增加了可以从数据中提取的信息。对线粒体DNA的分析将使我们能够追溯到遥远的历史，看看冰川的消长是如何推动森林遍布整个景观的。对叶绿体DNA的分析将揭示花粉流动的范围，并使我们能够确定不同的种群是否独立进化，或者基因流动是否将种群联系在一起，就好像它们之间的距离是一种幻觉。

The purpose of this research is to examine the geographic patterns of genetic variation in ponderosa pine and limber pine, with the goal of understanding how those geographic patterns were formed. This study takes advantage of unique patterns of inheritance in pines. Mitochondrial DNA (mtDNA) is inherited maternally and is dispersed only short distances in seeds. Chloroplast DNA (cpDNA) is inherited paternally, and has the potential to disperse great distances in wind-born pollen. Minimal gene flow of mtDNA allows it to detect genetic differences evolved between glacial refugia. High gene flow of cpDNA enables it to measure the degree of gene flow among populations. Sequence variation of mtDNA and cpDNA will be used to describe the variation across the ranges of both species. Biologists have studied geographic variation of plants and animals for centuries, but advances in molecular techniques have dramatically increased the information that can be collected from natural populations, and advances in the treatment of the data have dramatically increased the information that can be extracted from the data. Analyses of mtDNA will allow us to look far back into history, to see how the waxing and waning of the glaciers pushed forests across the landscape. Analyses of cpDNA will reveal the extent of pollen flow, and allow us to determine whether different populations evolve independently, or whether gene flow binds populations together, as if the distances among them were an illusion.