Global plant diversity patterns: case studies from early branching legume clades

最近的所有研究都表明，物种多样性在时间、地理区域和系统发育历史上的谱系之间分布非常均匀。尽管人们普遍认为，多样性的增加推动了物种多样化，但梳理多样性的原因仍然是一个挑战。我的实验室主要研究经济上重要的植物家族豆科（豆科）的系统学、系统发育和进化。豆科植物有765属，约19,500种，是第三大开花植物科，是植物进化多样化最引人注目的例子之一，几乎出现在全球每个生物群落中。我们主要研究这个家族的热带基系。我研究的长期目标是利用全面采样，稳健和良好解决的系统发生来建立稳定的分类，并更好地理解宏观进化形态，生态和生物地理模式。未来五年将实现三个目标。1)我们将研究全球多样化模式，以测试在五个基本豆科分支之间和内部的显著速率变化。为了实现这一目标，我们将使用系统基因组学方法对100个核基因进行测序，从而产生全面采样的系统发育。研究速率变化与地理、生物群系、功能性状和植物进化的关系。2)研究植物相关的内在特征，以检验性状依赖多样化。本研究将研究在花形态上表现出显著多样性的Detarioideae和Dialioideae两个谱系的花性状，并研究与生境适应相关的功能性状，其中Caesalpinioideae已经辐射到所有主要的生物群系。(3)对豆科植物的生物地理和生物群系演化进行研究，以确定这些主要的湿森林分支的分布是否可以追溯到早始新世至中始新世，干燥环境的多样化是否与大多数豆科植物一致。利用化石校准的系统发育，我们将研究当今的地理和生态分布，推断祖先的生物群系，寻找生物群系转移的证据，并批判性地评估生物群系保守性与地质历史在解释这两个分支分布中的相对重要性。我们最近的工作取得了重大进展，朝着更强大和稳定的基于系统发育的豆科植物分类。这里提出的研究为巩固这些努力提供了范围，以清楚地了解全球豆类多样性的模式。这个合作和广泛的研究项目为培养学生在植物系统学和进化方面的能力提供了机会，这对更好地了解世界范围内现有的生物多样性至关重要。

All recent studies suggest that species diversity is distributed very evenly through time, across geographical regions and amongst lineages in phylogenetic history. Although it is widely believed that increased variability drives species diversification, teasing apart the causes of diversification remains a challenge. Research in my laboratory focuses on systematics, phylogenetics and evolution of the economically important plant family Leguminosae (Fabaceae). With 765 genera and c. 19,500 species, legumes are the third largest flowering plant family, represent one of the most spectacular examples of evolutionary diversification in plants, and occur in nearly every biome across the globe. We study the mostly tropical basal lineages of the family. The long term objective of my research is to use comprehensively sampled, robust and well-resolved phylogenies to establish stable classifications and to better understand macro-evolutionary morphological, ecological and biogeographical patterns. Three objectives will be addressed in the next five years. 1) We will examine global patterns of diversification to test for significant rate shifts across and within the five basal legume clades. To achieve this, we will generate comprehensively sampled phylogenies using a phylogenomics approach to sequence 100's of nuclear genes. Rate shifts will be studied in relation to geography, biomes, functional traits and floral evolution. 2) Intrinsic plant-related characteristics will be studied to test for trait-dependent diversification. Floral characters will be examined in Detarioideae and Dialioideae, two lineages that exhibit remarkable diversity in floral morphology, and functional traits related to habitat adaptations will be studied in Caesalpinioideae, where radiations into all major biomes have occurred. 3) Biogeography and biome evolution will be studied in Detarioideae and Dialioideae to determine whether the distribution of these primarily wet forest clades can be traced to an early to mid-Eocene, dry environment diversification, as suggested for most legumes. Using fossil calibrated phylogenies, we will investigate present-day geographic and ecological distributions, infer ancestral biomes, look for evidence of biome shifts and critically evaluate the relative importance of biome conservatism versus geological history in explaining the distribution of these two clades. Our recent work has made significant progress towards a more robust and stable phylogenetically-based classification of legumes. The research proposed here offers scope to consolidate these efforts to clearly understand patterns of legume diversity across the globe. This collaborative and broadly based research program provides opportunities for training of students in plant systematics and evolution, which are essential to a better understanding of existing biodiversity worldwide.