Collaborative Research: Ecotypic Diversity and Adaptation of Prochlorococcus in the Stratified, High Temperature Waters of the Western Pacific Warm Pool

在大多数热带和亚热带生态系统中，原氯球菌在生态系统结构和生物地球化学中起着至关重要的作用，因为它是数量占优势的光自养微浮游生物。虽然人们普遍了解原氯球菌在世界范围内的分布，但其压倒性的生态成功的确切原因仍然难以捉摸。这一图景最近变得复杂起来，因为人们发现原氯球菌不是单系进化的，而且原氯球菌的不同遗传分支在深度和海洋盆地上的分布也有显著差异。因此，我们对自然环境中原氯球菌种群结构的因素的了解，以及我们预测这种结构如何对环境变化做出反应的能力是有限的。PIs将通过重点关注西太平洋暖池中自然发生的种群来解决这一问题，该地区已知原氯球菌占主导地位，但没有关于分支丰度的数据。西太平洋暖池(WPWP)除了是太平洋上一个对全球碳循环具有重要意义的大区域外，还特别令人感兴趣，因为它通常是高度分层的，与深海水相比，表层水具有极端的温度和光照水平。原氯球菌在表层和深层的种群承受着不同的环境压力，可能属于不同的分支，具有不同的适应生理。PI将在从新西兰克赖斯特彻奇通过分层WPWP前往夏威夷的邮轮上测试这一假设。这一样带的样本将被用来量化(使用定量PCR)原氯球菌的六个已知分支，并搜索新的分支(使用克隆文库和分离物)及其丰度。最终目标是将枝叶丰度与温度、光照、营养浓度和其他测量的生物、化学和物理变量联系起来。该项目将包括与科学家和整个科学界的多个层面的接触。数据和菌株将保存在国家储存库，结果将通过出版物、专业会议演示和项目网站传播。将对本科生和研究生进行培训，学生将成为数据收集、分析和传播阶段不可或缺的一部分，并将被鼓励在全国会议上发言。跨机构培训将促进研究生教育。PIS将把这一项目的成果纳入其本国机构的本科生和研究生课程，并将参加由国家科学基金会赞助的“K-16课堂上的科学研究”研讨会，以制定将结果与小学教育联系起来的方法。私人投资机构将与夏威夷科学院等当地外展团体合作，通过辅导、科学座谈会和中小学生科学竞赛等活动，促进科学理解。

In most tropical and subtropical ecosystems, the prokaryotic cyanobacteria Prochlorococcus plays a critical role in ecosystem structure and biogeochemistry because it is the numerically dominant photoautotrophic picoplankter. Although the worldwide distributions of Prochlorococcus are generally understood, the precise reasons for its overwhelming ecological success have remained elusive. This picture has recently become complicated by the discovery that Prochlorococcus is not monophyletic and that different genetic clades of Prochlorococcus have remarkably different distributions with depth and over oceanic basins. Thus, our understanding of factors that structure Prochlorococcus populations in the natural environment, and our ability to predict how this structure might respond to environmental changes, are limited. The PIs will address this by focusing on naturally occurring populations in the Western Pacific Warm Pool, an area where Prochlorococcus is known to dominate, but where there are no data on clade abundances. In addition to being a large region of the Pacific Ocean with significance to the global carbon cycle, the Western Pacific Warm Pool (WPWP) is of particular interest because it is typically highly stratified, with surface waters having extreme temperatures and light levels compared to those at depth. Populations of Prochlorococcus at the surface and at depth experience different environmental pressures, and may belong to different clades and have different adaptive physiologies. The PIs will test this hypothesis on a cruise from Christchurch, New Zealand to Hawaii through the stratified WPWP. Samples from this transect will be used to quantify (using quantitative PCR) the six known clades of Prochlorococcus and to search for new clades (using clone libraries and isolates) and their abundances. The ultimate goal is to relate clade abundances to temperature, light, nutrient concentrations and other measured biological, chemical and physical variables. This project will encompass multiple layers of outreach to scientists and the scientific community at large. Data and strains will be deposited at national repositories and results will be disseminated through publications, professional meeting presentations, and a project web site. Undergraduates and graduate students will be trained, and students will be an integral part of the data collection, analysis, and dissemination phases and will be encouraged to present at national meetings. Cross-institutional training will enhance graduate student education. The PIs will integrate results from this project into undergraduate and graduate curricula at their home institutions and will be attending the NSF sponsored 'Scientific Inquiry in the K-16 Classroom' seminar to develop methods to link results to primary education. The PIs will use presentations and activities with local outreach groups, such as the Hawaii Academy of Sciences, to encourage scientific understanding through mentoring, science symposia and science competitions for primary and secondary school students.