Molecular Differences, Adaptive Radiation, and Geographic Speciation in the Hawaiian Lobelioids

夏威夷的叶蕨亚科植物占夏威夷本土植物种类的九分之一。在那里，这些植物经历了惊人的辐射，在叶形、花形和种子传播适应方面具有惊人的独特性。大多数物种局限于单个岛屿，物种多样性似乎随着栖息地的改变而迅速消失。这些夏威夷物种之间的关系以及它们与其他太平洋半边纲的关系仍然存在争议。该项目将利用叶绿体和核DNA的序列数据来构建夏威夷半边莲的两个最大属的物种家谱，并解决与其他属和潜在祖先群体的关系。本研究的目标包括：1)建立一个基于分子的家谱，以非圆形的方式解释夏威夷小叶门的形态变异模式；2)确定基于分子数据的家谱与先前从形态学数据中提出的家谱之间的一致性，以评估用于夏威夷半山莲分类的形态学特征的可靠性；3)分析祖先与分布之间的联系，并推断为解释两个最大属的多样化所需的岛间扩散事件的数量；4)比较这些属的表观分子变化率，根据每个岛屿的地质年龄进行校准，并估计它们的大致起源时间和地点；5)评估夏威夷小叶门与其他类群及相关类群之间的关系，以确定夏威夷小叶门是否来自同一个祖先，并确定哪些被提出的类群与它们的起源有关。这项研究将为一种重要的、受到威胁的夏威夷本土植物群提供有关生物多样性及其起源的知识。＊＊＊

9509550 GIVNISH The plant subfamily Lobelioideae in Hawaii represents one-ninth of the plant species native to Hawaii. There these plants have undergone an amazing radiation with striking specializations in leaf shape, flower form and seed dispersal adaptations. Most species are restricted to individual islands and the species diversity seems to be rapidly disappearing with habitat alterations. Relationships among these Hawaiian species and the group's relationships to other Pacific lobelioids remain controversial. This project will utilize sequence data from both chloroplast and nuclear DNA to construct family trees for the species in the two largest genera of Hawaiian lobelioids and to address relationships to other genera and suggested ancestral groups. Goals of the study include: 1) deriving a molecular based family tree with which to interpret patterns of morphological variation in the Hawaiian lobelioids in a non-circular fashion; 2) determining the amount of agreement between family trees based on molecular data and those previously proposed from morphological data, in order to evaluate the reliability of the morphological traits that have been used to classify the Hawaiian lobelioids; 3) Analyzing the tie between ancestry and distribution and inferring the number of inter-island dispersal events required to account for the diversification seen in the two largest genera; 4) comparing the apparent rates of molecular change in these genera, calibrated against the geological ages of each island, and estimating their approximate time and place of origin; and 5) assessing the relationships of the Hawaiian lobelioids to each other and allied groups to determine if the Hawaiian lobelioids are descended from a single ancestor and identifying which of the proposed groups are implicated in their origin. %%% This study will provide knowledge on the biodiversity and its origins for an important and threatened group of native Hawaiian plants. ***