DISSERTATION RESEARCH: Biome conservatism in Neotropical plant diversification? A case study in Bignoniaceae

从两极到赤道，物种多样性在纬度上增加，使热带地区成为地球上物种最丰富的地区。新世界的热带植物——从墨西哥到阿根廷——孕育了前所未有的37%的维管植物物种。这种高度多样性的原因之一可能与该地区的历史有关。南美洲一直与其他大陆隔绝，直到大约3000万年前巴拿马地峡关闭。在此期间，地质事件和全球气候变化导致了许多生物群系的形成和维持，创造了一个异质景观，为孤立植物组合的成员提供了新的生态机会。本研究将产生新热带植物群的遗传和环境数据。这项工作的目标是更好地理解每个生物群系的进化模式是如何结合起来产生这种无与伦比的植物多样性水平的。这项工作将有助于记录新热带地区现有的生物多样性，并促进与拉丁美洲科学家的合作。研究成果将通过出版物传播，并通过博物馆展览和在线媒体的参与向更广泛的公众传播。本工作的重点是探索两种进化模式-生物群落保守性与生物群落转移-的平衡，以及它如何通过空间和时间影响新热带植物的多样化。生物群落保守性是指植物类群在多样化过程中保持相似环境并保留相应生态性状的趋势。这一模式表明，通过多样化取得的进化成功可能主要来自于生物群落的长期扩张或从起源点向类似生物群落的长距离迁移。另外，向新的生物群系的转变——生物群系进化——通过提供植物物种能够适应的新的生态位，可能对推动高多样化率至关重要。为了揭示新热带地区生物群落的保守性和变化规律，我们将在巴西和哥伦比亚进行野外工作，收集新热带大型植物科比格诺科的成员。利用基于扩增子的高通量测序技术和统计系统发育分析，该项目的目标是(A)检测大戟科植物的早期多样化事件，(B)估计多样化率，并将生物群落保守性和生物群落转移事件与这些多样化率联系起来。基于生态位可得性对适应的重要性，新占领的生物群系可得性的增加可能促进生物群系转移后物种形成和多样化率的显著增加。

Species diversity increases latitudinally from the poles to the equator, making the tropical regions the most species rich on Earth. New World tropical plants - from Mexico to Argentina - harbor an unprecedented 37% of vascular plant species. One of the reasons for this high diversity may lie in the history of the area. South America was isolated from other continental landmasses until about 3 Mya when the isthmus of Panama closed. During this period, geological events and global climate change led to the formation and maintenance of many biomes, creating a heterogeneous landscape with new ecological opportunities for members of the isolated plant assemblage to adapt. This research will generate genetic and environmental data from a group plants with a Neotropical distribution. The goal of this work is to better understand how the evolutionary patterns in each biome combine to generate this unparalleled level of plant diversity. This work will help document existing biodiversity in the Neotropics and foster collaboration with Latin American scientists. Research findings will be communicated via publications and to the broader public by participation in museum exhibits and online media.The focus of this work is to explore the balance of two evolutionary patterns - biome conservatism versus biome shifting- and how it has affected Neotropical plant diversification through space and time. Biome conservatism is the tendency of plant groups to remain in similar environments and retain corresponding ecological traits as they diversify. This pattern implies that evolutionary success through diversification may come primarily from biome expansion through time or long distance migration from point of origin to similar biomes. Alternatively, shifts into novel biomes- biome evolution- could be critical in driving high diversification rates by providing access to new ecological niches to which plant species can adapt. To unravel patterns of biome conservatism and biome shits in the Neotropics, field work will be conducted in Brazil and Colombia to collect members of the large Neotropical plant family Bignoniaceae. Using high-throughput amplicon-based sequencing techniques and statistical phylogenetic analyses, the goals are this project are to (A) detect early diversification events in Bignoniaceae and (B) estimate diversification rates and correlate biome conservatism and biome shift events with these diversification rates across the family. Based on the importance of niche availability to adaptation, increased opportunities available in newly occupied biomes may facilitate significant increases in speciation and diversification rate following biome shifts.