Doctoral Dissertation Research: The Pattern and Mode of Speciation in the Hawaiian Archipelago

岛屿生物区系的研究是现代地理学和进化生物学发展的核心。 在达尔文之前，19世纪世纪太平洋盆地的博物学家-探险家只是简单地将植物群和动物群的分布模式编目。 直到有了变异血统理论，才描述了岛屿内部和岛屿之间多样性的形成过程。 对岛屿生物区系的研究继续在理解进化过程，特别是物种形成过程方面发挥重要作用。 传统上，物种形成被认为是一个渐进的过程，两个被地理屏障分开的种群随着时间的推移积累差异。 然而，基于创始者事件的物种形成理论表明，物种形成可以比传统模型更快地进行。 亲本物种中存在的基因复合体可能由于随机抽样和少量的创始人而被破坏。 由于基因复合体的分裂，随着种群的增长，许多新的基因组合可能会在创始者事件之后不久出现。 随着选择作用于不断增长的种群，一个新的基因复合体将在创始种群中形成，从而产生一个新物种。 创始人介导的物种形成可能是海洋岛屿群体内的物种形成的主要模式，由于其孤立的性质。 以前的努力，以寻找分子遗传证据支持创始人事件物种形成模型受到了阻碍，有限的基因座，共同的遗传标记产生的和标准的人口遗传统计，这是为了描述人口之间的总遗传相似性，而不是由创始人效应模型预测的细微差别。 这个博士论文研究项目将研究夏威夷群岛特有的多年生草本植物的一个小谱系的物种形成，Lipochaeta部分Aphanopappus。 遗传多样性的模式将与扩增片段长度多态性（AFLP）的DNA技术进行检查，它可以产生一个数量级更多的遗传标记比以前使用的技术。 博士候选人将研究物种之间的进化关系，以确定岛屿中的物种形成模式，量化物种内和物种之间的遗传多样性，并研究与物种形成事件相关的基因复合体变化的遗传多样性模式。 对于后者的分析，她将使用一种新的统计方法来分析遗传数据。 该项目将提供有关遗传多样性的基本信息，以增强植物地理学理论。 研究结果也将是有价值的组内濒危物种的管理，并可能产生适用于其他濒危夏威夷生物群的管理见解。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

The study of island biota has been central to the development of biogeography and evolutionary biology as modern disciplines. Prior to Darwin, 19th century naturalist-explorers of the Pacific Basin simply catalogued the pattern of the distribution of flora and fauna. It was not until the theory of descent with modification that the process responsible for the diversity within and among islands was described. The study of island biota continues to play a major role in the understanding of evolutionary processes, particularly with regard to the process of speciation. Traditionally, speciation is thought to be a gradual process whereby two populations split by a geographic barrier accumulate differences over time. Theories of speciation based on founder events have suggested, however, that speciation can proceed much more rapidly than with the traditional model. The gene complexes present in the parental species presumably become disrupted due to the random sampling and small number of founders. Because of the breakup of gene complexes, many novel gene combinations may be present soon after the founder event as the population grows. As selection acts on the growing population, a novel gene complex will form in the founding population, resulting in the creation of a new species. Founder-mediated speciation may be the dominant mode of speciation within oceanic island groups owing to their isolated nature. Previous efforts to find molecular genetic evidence supporting founder-event speciation models have been hampered by the limited number of loci that common genetic markers generated and by standard population genetic statistics, which were designed to describe gross genetic similarity among populations and not the nuances predicted by founder-effect models. This doctoral dissertation research project will examine speciation in a small lineage of perennial herbs endemic to the Hawaiian islands, Lipochaeta section Aphanopappus. Patterns of genetic diversity will be examined with the DNA technique of amplified fragment-length polymorphisms (AFLPs), which can generate an order of magnitude greater number of genetic markers than previously used techniques. The doctoral candidate will examine evolutionary relationships among species to determine patterns of speciation in the islands, quantify genetic diversity within and among species, and examine patterns of genetic diversity for changes in gene complexes associated with speciation events. For the latter analysis, she will use a statistical approach novel to the analysis of genetic data. This project will provide basic information about genetic diversity that will enhance biogeographic theory. The results also will be valuable for the management of endangered species within the group and may yield insights applicable to the management of other endangered Hawaiian biota. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.