Dissertation Research: Systematics, biogeography and taxonomy of the pantropical legume genus Cynometra

豆科植物是开花植物的第三大科。这些具有重要经济和生态意义的植物大小不一，从微小的沙漠草本植物到巨大的雨林树木。虽然最近的研究已经阐明了该家族主要谱系之间的关系，但对近2万个物种中的许多物种知之甚少，尤其是产生这种多样性的过程。这项研究将使用最近开发的“下一代”DNA测序方法和统计计算机模型来解决大型和广泛分布的热带豆科植物群体之间的进化关系，并推断对新环境的适应在这些物种的多样化中发挥了什么作用，如果有的话。鉴于其广泛的分布和生态多样性，了解这些物种之间的关系将为未来的比较研究提供一个框架，并增强我们对豆科植物整体进化的理解。该项目还将包括一个重要的培训部分，让STEM领域的本科生了解最新的工具和分析方法。本研究将结合系统基因组学、生态位模型和化石记录信息，阐明热带属Cynometra和Maniltoa物种之间的关系，并探讨生态位保守性在生物地理学和物种形成机制中的作用。下一代测序正在彻底改变系统学、生物地理学和进化生物学的实践。虽然该技术已经应用于非常深和非常浅的进化问题，但它在物种水平的系统发育上的应用，特别是在植物中，仍然有限。然而，在物种水平上，这些新技术最有希望解决以前棘手的关系。此外，当与生态位模型和地理范围数据相结合时，这些方法能够产生很好的系统发生，使研究人员能够研究物种形成机制和生态位保守性在产生观察到的多样性模式中的作用。例如，如果异域姐妹种始终沿着环境轴分离，那么生态介导的选择可能在物种形成中起作用，而如果异域姐妹种在非生物生态位空间中始终相同或几乎相同，那么生态分化就不是驱动物种形成的主要因素。为了解决这一问题，研究人员将：1)在巴西（属的多样性中心）进行实地调查和访问植物标本馆，以更好地表征巴西物种的多样性和分布；2)利用目标序列捕获技术生成的数据重建一个很好的物种水平的系统发育；3)利用生态位模型和分布数据对组成物种的非生物生态位进行表征。对这些数据的分析将提供对Cynometra和Maniltoa的进化和生物地理历史以及驱动这些过程的机制的更精确的理解。

Legumes are the third largest family of flowering plants. These economically and ecologically significant plants range in size from tiny desert herbs to giant rainforest trees. While recent research has elucidated relationships among the major lineages in the family, little is known about many of the nearly 20,000 species, especially the processes that generate this diversity. This study will use recently developed 'next generation' DNA sequencing methods and statistical computer modeling to resolve the evolutionary relationships among a large and widespread group of tropical legumes and to infer what role, if any, adaptation to new environments has played in the diversification of these species. Given their wide distribution and ecological diversity, understanding the relationships among these species will provide a framework for future comparative studies and enhance our understanding of the overall evolution of the legume family. The project will also include a significant training component to expose undergraduates in STEM fields to the latest tools and analytic methods.This study will combine phylogenomics, ecological niche modeling, and information from the fossil record to elucidate the relationships among the species of the tropical genera Cynometra and Maniltoa and will investigate the role niche conservatism plays in biogeography and speciation mechanisms. Next generation sequencing is revolutionizing the practice of systematics, biogeography, and evolutionary biology. While the technology has been applied to both very deep and very shallow evolutionary questions, its application to species level phylogenetics, particularly in plants, remains limited. However, it is at the species level that these new techniques hold the greatest promise to resolve previously intractable relationships. In addition, when combined with ecological niche modeling and geographic range data, the well resolved phylogenies these methods are capable of producing allow researchers to study speciation mechanisms and the role of niche conservatism in generating observed patterns of diversity. If, for example, allopatric sister species consistently segregate along environmental axes, then ecologically mediated selection may have a role in speciation, whereas if allopatric sister species are consistently identical or nearly identical in abiotic niche space, then ecological divergence is not a major factor driving speciation. To address this question, the researchers will: 1) conduct field work and visit herbaria in Brazil (the center of diversity for the genus) to better characterize diversity and distributions of Brazilian species; 2) reconstruct a well resolved species level phylogeny using data generated with targeted sequence capture techniques; and 3) characterize the abiotic niche of the constituent species using ecological niche modeling and distribution data. Analyses of these data will provide a much more precise understanding of evolutionary and biogeographic history of Cynometra and Maniltoa and the mechanisms driving these processes.