DISSERTATION RESEARCH: Speciation and hybridization in the moss genus Sphagnum

部分可育的种间杂交种可以作为研究亲本种间基因流动的模型。苔藓植物（苔藓、苔类植物和角苔类植物）的二倍体和单倍体都很发达，通过对单倍体产生的重组配子体的遗传分析，为记录二倍体的种间杂交提供了一个很好的系统。本研究将重点研究两个近缘种Sphagnum macrophyllum和S. cribrosum的基因流。通过对部分可育的种间杂交种产生的重组配子体的遗传分析，可以确定近亲物种之间的生殖隔离程度。将在它们的活动范围内收集样本，在这两种物种同时出现的地方，以及在它们不同时出现的地方。最近发现的两个物种配子体密切杂交的地点为在最有可能发生的情况下测试物种之间的基因流动提供了一个绝佳的机会。样本中的基因流动将使用基因组极端可变延伸的DNA标记进行评估。数据分析将测试人口遗传学中涉及人口规模和迁移率的最新先进的聚结模型。这项研究将提高我们对这一生态和经济上重要的苔藓类群的进化史的理解。此外，它还将有助于更好地理解涉及物种形成的复杂过程。该奖项为学生研究者提供了加强博士论文研究的机会，并与他人分享他的发现。

Partially fertile, interspecific hybrids of mosses can serve as a model for studying gene flow between parent species. The bryophyte (moss, liverworts and hornworts) life cycle, in which both diploid and haploid generations are well developed, provides an excellent system in which to document interspecific hybridization in the diploid generation through genetic analysis of the resulting recombinant gametophytes in the haploid generation. This investigation of gene flow will focus on two closely related species of Sphagnum moss (Sphagnum macrophyllum and S. cribrosum). The amount of reproductive isolation between closely related species can be determined through genetic analyses of the recombinant gametophytes produced by their partially fertile, interspecific hybrids. Samples will be collected throughout their ranges where the two species occur together and where they do not. The recent discovery of a site where gametophytes of both species are intimately intermixed provides an exceptional opportunity to test for gene flow between species under circumstances where it is most likely to occur. Gene flow in the samples will be evaluated using DNA markers in extremely variable stretches of the genome. Data analyses will test newly advanced coalescence models in population genetics that involve population size and migration rates. This study will improve our understanding of the evolutionary history of this ecologically and economically important group of mosses. In addition, it will also lead to a better understanding of the complex processes involved in speciation. This award provides the student investigator opportunities to enhance his doctoral dissertation study and share his discoveries with others.