Speciation and extinction risk in the vascular plants of Canada

在加拿大已知的5211种维管植物中，有超过650种处于某种程度的灭绝风险。确定每个物种的风险水平是一项耗时的奋进，导致科学家试图设计灭绝风险的预测因子，以产生值得立即关注的候选物种的短名单。 我们刚刚开始了解基因组是如何随着物种形成而改变的，以及它如何影响生物体的表型。虽然动物物种很少能容忍它们基因组中的额外染色体（例如，大多数人的“三体”导致流产或发育障碍），植物很容易整合整个额外的染色体组。这个过程可能导致物种形成，因为具有额外染色体组（多倍体）的个体通常不能与其二倍体（两组染色体）亲属产生可存活的后代。多倍体物种在适应环境变化的能力上是否表现出差异尚不清楚。该提案旨在揭示多倍体物种形成对加拿大境内植物物种灭绝风险的影响，有三个短期目标。 在第一个目标，我将产生更好的估计率的多倍体物种形成在重要的加拿大血统。大约有42种维管植物是加拿大特有的，其中许多是加拿大植物群的成员，如柳树、山楂和一枝黄花。尽管已经建立了确定基因组大小的方法，但这些属有>50%的物种具有未知的倍性。我的实验室将使用流式细胞术，物种分布建模和遗传学来确定多倍体化在这些谱系的进化历史中发生的位置，然后测试这些过程如何影响其当前灭绝风险的假设。 在第二个目标中，我们将调查花物候的变化，在不同倍性水平的显花植物，利用植物标本记录性状的变化，在过去的世纪。最后，在第三个目标中，我将研究授粉是如何改变倍性的变化。多倍体被认为是更经常自我兼容和较少依赖于传粉者，这些差异可能是至关重要的预测人口将如何应对生态变化，如气候变暖或栖息地改造。 目前，我们缺乏关于加拿大面临风险的物种是否是不成比例的多倍体或最近起源的信息。这些问题的答案将有助于我们理解是什么驱动了物种形成和灭绝率的差异，但也将导致有效的政策，优先物种的保护工作。该提案将研究加拿大特有的维管植物物种的进化历史，以揭示物种形成历史，多倍化和专业化的作用，使物种容易受到人类干扰。

Of the 5211 known species of vascular plants in Canada, there are >650 at some level of risk of extinction. Determining the level of risk for each species is a time-consuming endeavor, leading scientists to attempt to devise predictors of extinction risk to produce short-lists of candidate species deserving the most immediate attention. We are just beginning to understand how the genome is altered with speciation and how it affects the phenotype of an organism. While animal species can rarely tolerate an extra chromosome in their genomes (e.g., most human "trisomies" result in miscarriage or developmental disorders), plants readily incorporate an entire extra chromosomal set. This process can result in speciation because the individuals with extra chromosome sets (polyploids) often cannot produce viable offspring with their diploid (two sets of chromosomes) relatives. Whether polyploid species exhibit differences in their ability to adapt to changing environments is not understood. This proposal aims to uncover the consequences of polyploid speciation to the extinction risk of plant species within Canada with three short-term objectives. In the first objective, I will produce better estimates of the rate of polyploid speciation in important Canadian lineages. There are approximately 42 vascular plant species endemic to Canada, and many are members of familiar elements of the Canadian flora, such as the willows, hawthorns, and goldenrods. Despite established methodology for determining genome size, these genera have >50% of their species with unknown ploidy. My lab will use flow cytometry, species distribution modelling, and phylogenetics to identify where polyploidization has occurred in the evolutionary history of these lineages and then test hypotheses of how these processes have affected their current extinction risk. In the second objective, we will survey the change in floral phenology amongst flowering plants with different ploidy levels using herbarium specimens to document trait change over the past century. Finally, in the third objective, I will examine how pollination is altered upon shifts in ploidy. Polyploids are thought to be more often self-compatible and less dependent on pollinators and these differences may be critical in predicting how populations will respond to ecological changes such as climatic warming or habitat modification. Currently, we lack information on whether species-at-risk in Canada are disproportionately polyploid, or of recent origin. Answers to these questions will contribute to our understanding of what drives differences in speciation and extinction rate, but will also lead to effective policy for prioritizing species for conservation effort. This proposal will examine Canada's endemic vascular plant species in terms of their evolutionary history to uncover the role of speciation history, polyploidization, and specialization in making species vulnerable to human disturbance.