Phylogeny and Biogeography of the Dichrostachys Group (Mimosideae Leguminosae) in Madagascar: Evidence from Morphological and Molecular Studies

9726981马达加斯加Dichrostachys群(含羞亚科：豆科)的Luckow系统发育和生物地理：形态和分子研究的证据。马达加斯加生物群是地球上最多样化的生物群之一，无论是使用物种的原始数量、独特特征或系统发育位置来衡量生物多样性。据报道，在一个长约1000英里，宽约360英里的地区，估计有超过1万种开花植物，而且大量的特有物种往往具有在其他地区原生的相关类群中未曾见过的极端形态创新。因此，马达加斯加提供了一个理想的系统，用来研究影响物种形成和形态多样性和精细化的因素。Dichrostachys群由三个属的拟态豆科植物组成，广泛辐射整个马达加斯加，大约30个物种中，除了3个物种外，其余都是该岛特有的物种。该组织为研究马达加斯加植物的进化提供了一个模式系统，因为马达加斯加有大量的物种，而且它们广泛分布在马达加斯加干燥、季节性干燥和潮湿的森林中。基于分子和形态数据的系统发育分析将用于解决与系统学、授粉和生物地理学相关的问题。属的界限在Dichrostachys群中一直存在争议，系统发育将作为定义单系属的基础。授粉者的转移和传粉者与花序颜色和其他花卉性状的变化的相关性将被检查。特别令人感兴趣的将是马达加斯加引进的一个物种的传粉者与南非本土种群的传粉者的比较。特别是，这将允许我们探索这样的问题：花序颜色的变化是否伴随着传粉者的变化？个体发育的颜色变化是否与传粉者的转移有关？该系统发育还将用于马达加斯加特有地区的生物地理学研究。具体而言，拟议的生物地理研究将探讨物种形成和地质过程之间的关系，解决以下问题：马达加斯加的土壤类型和物种形成之间是否存在相关性？这是一种可以在不相关的群体中衡量的普遍现象吗？是否存在系统发育和地质事件的对应关系，表明物种形成随时间推移的一般模式？这项调查还将以专著、传粉者的计数和物种分布的详细地图的形式提供主要的描述性数据。物种分布的详细地图可以用来证实或驳斥最近利用卫星图像对主要植被类型进行分类的概括。Dichrostachys组从未被专著发表过，而且有科学上的新物种以及关于以前描述的物种的新信息。马达加斯加的生物群目前是世界上最受威胁的生物群之一，迫切需要这项工作。

9726981 Luckow Phylogeny and biogeography of the Dichrostachys group (Mimosoideae:Leguminosae) in Madagascar: evidence from morphological and molecular studies. The Madagascan biota qualifies as one of the most diverse on earth, whether one measures biodiversity using raw numbers of species, unique features, or phylogenetic position. Estimates of over 10,000 species of flowering plants have been reported from an area about 1000 miles long and 360 miles wide, and the large number of endemic species often possess extreme morphological innovations not seen in related taxa native to other regions. Thus, Madagascar offers an ideal system in which to investigate the factors influencing both speciation and morphological diversity and elaboration. An assemblage of three genera of mimosoid legumes, the Dichrostachys group has radiated widely throughout Madagascar, with all but three of approximately 30 species endemic to the island. The group provides a model system for investigating the evolution of Malagasy plants both because there are a large number of species and because they are widely distributed throughout the dry, seasonally dry, and moist forests of Madagascar. Phylogenetic analyses based on molecular and morphological data will be used to address questions relevant to systematics, pollination, and biogeography. Generic boundaries have been controversial in the Dichrostachys group, and the phylogeny will serve as a basis to define monophyletic genera. Pollinator shifts and correlations of pollinators with changes in inflorescence color and other floral traits will be examined. Of special interest will be the comparison of the pollinators of one introduced species both in Madagascan and in native South African populations. In particular this will permit us to explore such questions as: are changes in inflorescence color accompanied by a shift in pollinators? Are ontogenetic color changes associated with pollinator shifts? The phylogeny will also be used in biogeographic stu dies of areas of endemism within Madagascar. Specifically, the proposed biogeographic study will explore the relationship between speciation and geological processes, addressing questions such as: Is there a correlation between soil type and speciation in Madagascar? Is this a general phenomenon that can be measured across unrelated groups? Is there correspondence of phylogenies and geologic events indicating a general pattern of speciation through time? This investigation also will contribute primary descriptive data in the form of a monograph, an enumeration of pollinators, and the detailed mapping of species distributions. The detailed mapping of species distributions can be used to corroborate or refute generalizations about the primary vegetation types that recently have been classified using satellite imagery. The Dichrostachys group has never been monographed and there are species new to science as well as new information on previously described species. The biota of Madagascar is currently one of the most threatened in the world and the need for this work is urgent.