MtDNA and cpDNA Phylogeographies of Ponderosa Pine and Limber Pine

本研究旨在探讨黄松和松木遗传变异的地理格局，以了解这些地理格局是如何形成的。本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，仅在种子中短距离分散。叶绿体DNA （cpDNA）是父系遗传的，在风传花粉中具有远距离传播的潜力。mtDNA的最小基因流使它能够检测冰川避难所之间进化的遗传差异。cpDNA的高基因流量使其能够测量种群间的基因流动程度。mtDNA和cpDNA的序列变异将用于描述两种物种范围内的变异。几个世纪以来，生物学家一直在研究动植物的地理变异，但分子技术的进步极大地增加了从自然种群中收集到的信息，而数据处理的进步也极大地增加了从数据中提取的信息。对mtDNA的分析将使我们能够回顾历史，了解冰川的盛衰如何推动森林遍布整个景观。对cpDNA的分析将揭示花粉流动的程度，并使我们能够确定不同的种群是独立进化的，还是基因流动将种群联系在一起，就好像它们之间的距离是一种错觉。

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.