Systematics, biogeography and evolution of northern floras

系统学的一个中心目标是确定形成跨越空间和时间的多样性的过程。北部的植物群提供了这样做的有趣机会，因为它们经历了过去气候变化最剧烈的一些时期。我的长期研究目标是发现、分类和保护令人敬畏的北方植物的生物多样性，并确定负责产生和维持这种多样性的过程。为了实现这一目标，我将重点关注三个短期目标，这些目标将在三个进化尺度上阐明过去气候变化对北方植物群进化的影响：宏观进化（目标1）、微观进化（目标2）和生态（目标3）。目标1是量化历史气候变化对化石记录中最丰富的植物科之一——苏科（约1000块化石）的多样性和进化的影响。我们将首先对所有文献报道的化石建立一个全面的数据库，并通过几何形态计量学分析（BSc 1）重新评估它们的分类亲和力。由此产生的被子植物化石数据集将具有前所未有的规模和质量，可以对过去1亿年来跨越苏科进化史的植物多样化动态、生物地理学、生态位进化和果实进化进行高分辨率分析。目的2是开发第一批苏科基因组资源，并利用它们来确定气候如何影响杂交和渐渗频率。两个Carex基因组将以低成本从一个实验性杂交组合组装到染色体尺度（PhD 1），这将允许估计古代基因渗入事件的时间和强度，基于渗入的基因组块的长度。我们还将利用优先寄生于杂交种的炭疽科真菌作为代理来推断深时间杂交频率（Msc 2），扩展我们之前对苏科寄主-寄生虫相互作用的研究。目标3将加速淡水潮汐植物群的分类研究，这是一个丰富但受到威胁的北美特有中心。通过对该植物区系特有的两个Cyperaceae （BSc 2, MSc 3）和一个Asteraceae （PhD 2）谱系的平行分类和群体基因组研究，我们将发现遗传多样性的共享模式，可用于在最不同的种群和地区优先保护。然后，我们将建立一个完整的分布数据库，包括淡水潮汐区系中出现的所有分类群（约100种；BSc 3），以测试面积、气候条件和河口之间的距离如何影响特有性、丰富度、系统发育多样性和种群遗传多样性（博士2）。这种结合的方法将使我们能够发现大规模的历史和生态过程，这些过程在生物复杂性的各个层面上形成多样性，从基因到物种和整个群落。

A central aim of systematics is to identify the processes that shape diversity across space and time. Northern floras offer interesting opportunities to do so, as they have been through some of the most intense periods of past climate change. My long term research goal is to discover, classify and protect the awe-inspiring biodiversity of northern plants, and to identify the processes responsible for generating and maintaining this diversity. Towards this goal, I will focus on three short-term objectives that will shed light on the impact of past climate change on evolution of northern floras at three evolutionary scales: macro-evolutionary (Objective 1), micro-evolutionary (Objective 2), and ecological (Objective 3). Objective 1 is to quantify the influence of historical climate change on the diversity and evolution of one of the most abundant plant families in the fossil record, Cyperaceae (>1000 fossils). We will first compile a comprehensive database of all fossils reported in the literature, and re-assess their taxonomic affinities through geometric morphometric analysis (BSc 1). The resulting fossil dataset will be of unprecedented size and quality in angiosperms, enabling high-resolution analysis of plant diversification dynamics, biogeography, niche evolution and fruit evolution throughout the last 100 million years that span the evolutionary history of Cyperaceae (MSc 1). Objective 2 is to develop the first genomic resources for Cyperaceae, and to use them to determine how climate influences the frequency of hybridization and introgression. Two Carex genomes will be assembled to chromosome-scale (PhD 1) at low cost from an experimental hybrid, which will allow estimation of the timing and intensity of ancient introgression events, based on the lengths of introgressed genomic blocks. We will also expand on our previous investigations of host-parasite interactions in Cyperaceae by utilizing Anthracoidea fungi, which preferentially parasitize hybrids, as a proxy to infer the frequency of hybridization in deep time (Msc 2). Objective 3 will be to accelerate taxonomic research on the Freshwater Tidal Flora, a rich but threatened North American centre of endemism. Through parallel taxonomic and population genomic studies of two Cyperaceae (BSc 2, MSc 3) and one Asteraceae (PhD 2) lineage endemic to this Flora, we will discover shared patterns of genetic diversity that can be used to prioritize conservation on the most distinct populations and areas. We will then assemble a complete distribution database of all taxa occurring in the Freshwater Tidal Flora (c. 100 species; BSc 3) to test how area, climatic conditions and distance between estuaries affect endemicity, richness, phylogenetic diversity, and population genetic diversity (PhD 2). This combined approach will allow us to discover large-scale historical and ecological processes that shape diversity at all levels of biological complexity, from genes to species and whole communities.