Floral evolution and biogeography in early diverging legume lineages

拟议的研究计划侧重于属于豆科(豌豆和豆科)、凯撒亚科的热带树种早期分化的谱系的进化和系统学。其目的是重建这个亚科的进化史，并检验关于花和营养形态的进化、多样性速率和生物地理的假说。豆科植物有近2万种，是被子植物中第三大、经济上最重要的科之一。传统上，豆科植物被认为由三个亚科组成，即凯撒亚科、含羞亚科和凤蝶亚科。在这三个亚科中，Caesalpinioideae一直是分类和系统发育研究最少的。这些豆科的早期分支在花卉和营养形态上具有高度的多样性，并广泛分布于世界各地，其化石记录可以追溯到始新世。它们还包括一些最初的分歧谱系，其中包括固定氮的物种。利用来自叶绿体和核基因组的分子数据，并建立在我们以前在亚科中的工作基础上，我们将识别自然类群并确定属之间的关系。这将作为一个框架，建立一个新的，急需的，分类系统的凯撒皮亚科。这一新的分类将使我们能够探索花卉和营养植物进化的模式、生物地理模式和分子进化。化石将被用来记录血统的最小年龄，作为检验生物地理假说的历史点，并作为估计分类学和分子多样性比率的基础。这项拟议的研究是旨在研究这种鲜为人知但在生态和分类学上具有重要意义的豆科早期分化谱系之间的关系的国际合作的核心。我们的作用是为比较目的提供强有力的系统发育支持，目的是研究这一不同类群的花粉形态、木材解剖、花个体发育和结瘤的进化。

The proposed research program focuses on the evolution and systematics of early diverging lineages of tropical tree species belonging to the family Leguminosae (pea and bean family), subfamily Caesalpinioideae. The objectives are to reconstruct the evolutionary history of this subfamily and to test hypotheses concerning the evolution of floral and vegetative morphology, rates of diversification and biogeography. With nearly 20,000 species, the Leguminosae is the third largest and economically one of the most important of angiosperm families. Traditionally the Leguminosae is considered to comprise three subfamilies, the Caesalpinioideae, Mimosoideae and Papilionoideae. Of the three subfamilies, the Caesalpinioideae has been the most poorly studied taxonomically and phylogenetically. These early offshoots of the Leguminosae are highly diverse in their floral and vegetative morphology and widely distributed in the world with a fossil record that dates to the Eocene. They also encompass some of the first diverging lineages that include species which fix nitrogen. Using molecular data derived from the chloroplast and nuclear genomes, and building upon our previous work in the subfamily, we will identify natural groups and determine relationships among genera. This will serve as a framework for establishing a new, badly needed, classification system for the Caesalpinioideae. This new classification will allow us to explore patterns of floral and vegetative evolution, biogeographic patterns, and molecular evolution. Fossils will be used to document minimum ages of lineages, as historical points for testing biogeographical hypotheses, and as a basis for estimating taxonomic and molecular diversification rates. The proposed research is central to an international collaboration aimed at examining relationships in this poorly known, yet ecologically and taxonomically important, early diverging lineages of the Leguminosae. Our role is to provide a strongly supported phylogeny for comparative purposes with the aim of studying the evolution of pollen morphology, wood anatomy, floral ontogeny and nodulation in this diverse group of taxa.