Dissertation Research: Population Structure in Ponderosa Pine

小行星9520381 植物种群的有效管理（无论是出于经济还是保护目的）需要了解种群之间的遗传差异，因为这些差异可能反映了每个种群对当地环境的适应。 我们对种群分化的理解大多来自于对蛋白质基因的研究。 这项拟议的研究将利用最新的DNA技术，比较发现从蛋白质基因的其他类型的基因，在自然种群的黄松。 数据收集是简单的，包括测量数量的遗传分化的种群之间的南北样带通过从西南部的黄松的范围。 遗传差异是通过确定DNA类型（“等位基因”）的频率在每个种群的研究，从样品的针组织带回实验室。 这项研究将从两个方面促进我们的理解。 首先，通过比较不同类型的基因之间的遗传差异模式，可以检验更早的发现。 理论预测，种群间遗传差异的大小将由种群间迁移和杂交的数量决定。 由于所有基因的迁移量都是相同的，因此所有基因座在种群之间应该表现出相同的差异幅度。如果没有，那么“不适合”的基因可能会受到其他因素的影响，例如适应当地条件的选择。 其次，这项研究将比较那些从父母双方遗传的基因（大多数基因）和那些只从父母一方遗传的基因。 松树提供了一个独特的机会，因为叶绿体DNA是父系遗传的（通过花粉），而线粒体DNA是母系遗传的（通过种子）。 通过比较具有这些不同遗传模式的群体之间基因的相对差异，研究人员可以测量种子和花粉的相对迁移量。 理解这一点很重要，因为只有种子迁移者才能发现新的种群，而迁移花粉仅限于在现有种群之间移动。

9520381 Mitton Effective management of plant populations (either for economic or conservation purposes) requires an understanding of the genetic differences among populations, since these differences may reflect adaptation to the local environments in which each population lives. Much of our understanding of population differentiation has been derived from the study of protein genes. This proposed research will make use of recent DNA technologies to compare the findilgs from protein genes to other types of gene, in natural populations of ponderosa pine. The data collection is straightforward, and consists of measuring the amount of genetic differentiation between populations in a north-south transect through the range of ponderosa pine from the Southwest. Genetic differences are measured by determining the frequency of DNA types ("alleles") in each population under study, from samples of needle tissue brought back to the laboratory. This study will advance our understanding in two ways. First, by comparing patterns of genetic differences between different types of genes, older findings can be tested. Theory predicts that the size of genetic differences among populations will be determined by the amount of migration and interbreeding between them. Since the amount of migration is the same for all genes, all loci should show the same magnitude of difference between populations. If not, then genes which "don't fit" are likely to be affected by some other factor, such as selection to adapt to local conditions. Second, the study will compare those genes inherited from both parents (most genes) with those inherited solely from one parent. Pines provide a unique opportunity to do this in that chloroplast DNA is inherited paternally (through the pollen), while mitochondrial DNA is maternally inherited (through the seed). By comparing the relative differences between populations for genes with these contrasting inheritance patterns, the investigators can measure the relative amount of mig ration by both seeds and pollen. It is important to understand this, because only seed migrants can found new populations, while migrant pollen is restricted to movement between existing populations.