DISSERTATION RESEARCH: Phylogeny, reticulate evolution, and historical biogeography in the Hawaiian lobeliad genera Cyanea and Clermontia

适应性辐射，即一组生物体通过辐射发挥一些生态作用，为研究物种在有限地理区域内迅速多样化的机制提供了机会。半边莲属植物（半边莲科）仅限于夏威夷群岛的成员经历了显着的差异，在生境，生长形式，叶的大小和形状，花的形态，种子传播的机制，并被认为是最好的例子之一，适应辐射的植物。先前的研究表明，这140个物种来自1300万年前的单一殖民地，早在今天的许多夏威夷岛屿从太平洋出现之前。夏威夷半边莲现在占夏威夷本土植物群的12%，是地球上任何一组海洋岛屿上发现的物种最丰富的植物谱系。两个最大的属，Cyanea和Clermontia，包括大约100个物种，形成了该组中最大的亚系。以前的系统发育分析Cyanea-Clermontia是不确定的，由于组内有限的采样和不充分的DNA序列变异的组合，以重建一个良好的支持估计的关系。Cyanea-Clermontia的大小，生态和形态多样性，以及高比例的物种仅限于单个岛屿（每个已知年龄），为研究适应性辐射，物种形成和历史地理学提供了独特的机会。了解这一谱系内的关系可以为夏威夷动植物多样性的兴起提供新的见解，并确定与稀有或灭绝趋势相关的特征。该项目将（1）在植物系统学和历史植物地理学分析方面对一名研究生进行广泛培训;（2）开发分子系统发育分析管道，以协助对其他近期辐射的研究;（3）制作一批有充分记录的DNA样本，以便今后对这一重要群体进行研究;以及（4）创建一个关于夏威夷本土半边莲多样化的网站，向广大的业余植物学家和半边莲爱好者传播研究成果。接下来-第二代DNA测序数据将用于从整个叶绿体基因组和400个核基因中推断Cyanea-Clermontia的遗传。这些数据的分析将允许衍生的物种树和网络，杂交，基因渗入，和其他形式的网状进化（重要的克莱蒙蒂亚）的分析，重建其地理传播通过时间，并推断模式和节奏的关键形态和生态特征的状态，使用各种树和网络为基础的方法。

Adaptive radiations, where a group of organisms has radiated to perform a number of ecological roles, offer an opportunity to investigate the mechanisms that allow species to diversify rapidly within a limited geographical area. Members of the lobelia plant family (Lobeliaceae) restricted to the Hawaiian Islands have undergone a remarkable divergence in habitat, growth form, leaf size and shape, floral morphology, and mechanism of seed dispersal, and are considered one of the best examples of an adaptive radiation in plants. Previous studies have shown that this group of 140 species was derived from a single colonization 13 million years ago, long before many of the Hawaiian islands of today had emerged from the Pacific. Hawaiian lobeliads now represent 12% of the native Hawaiian flora and are the most species-rich plant lineage found on any single group of oceanic islands on Earth. The two largest genera, Cyanea and Clermontia, comprising approximately 100 species form the largest sublineage within the group. Previous phylogenetic analyses of Cyanea-Clermontia were inconclusive due to a combination of limited sampling within the group and insufficient DNA sequence variation to reconstruct a well-supported estimate of relationships. Cyanea-Clermontia, by its very size, ecological and morphological diversity, and high proportion of species restricted to single islands (each of known age), offers unique opportunities for studying adaptive radiation, speciation, and historical biogeography. Understanding relationships within this lineage could provide new insights into the rise of plant and animal diversity on Hawaii, and identify traits associated with a tendency to become rare or extinct. This project will (1) broadly train a graduate student in plant systematics and historical biogeography analyses; (2) develop molecular phylogenetic analysis pipelines to aid in the study of other recent radiations; (3) produce a well-documented collection of DNA samples to permit future studies of this important group; and (4) create a website on the diversification of native Hawaiian lobeliads, to disseminate findings to a broad range of amateur botanists and lobeliad enthusiasts.Next-generation DNA sequencing data will be used to infer phylogenies of Cyanea-Clermontia from whole-chloroplast genomes and 400 nuclear genes for all living species sampled across their range. Analyses of these data will permit derivation of species trees and networks, analysis of hybridization, introgression, and other forms of reticulate evolution (important in Clermontia), reconstruct its geographic spread through time, and infer the pattern and tempo of evolution of key morphological and ecological character-states using a variety of tree- and network-based approaches.