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

在大多数热带和亚热带生态系统中，原绿球藻在生态系统结构和生物地球化学中起着至关重要的作用，因为它是数量上占主导地位的光自养微浮游生物。虽然原绿球藻在世界范围内的分布已被普遍了解，但其压倒性的生态成功的确切原因仍然难以捉摸。由于发现原绿球藻不是单系的，并且原绿球藻的不同遗传枝在不同深度和海洋盆地上的分布有显著不同，这一情况最近变得复杂起来。因此，我们对自然环境中原绿球藻种群结构因素的理解，以及我们预测这种结构如何应对环境变化的能力，都是有限的。PIs将通过关注西太平洋暖池中自然发生的种群来解决这个问题，该区域已知原绿球藻占主导地位，但没有分支丰度的数据。西太平洋暖池（WPWP）除了是太平洋的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，与深处相比，地表水具有极端的温度和光照水平。原绿球藻在水面和深海的种群承受着不同的环境压力，可能属于不同的支系，具有不同的适应生理。pi将在从新西兰克赖斯特彻奇到夏威夷的游轮上通过分层的WPWP来验证这一假设。该样带的样品将用于定量（使用定量PCR）原绿球藻的六个已知分支，并寻找新的分支（使用克隆文库和分离株）及其丰度。最终目标是将进化支的丰度与温度、光照、营养物质浓度和其他可测量的生物、化学和物理变量联系起来。这个项目将包括对科学家和整个科学界的多个层面的延伸。数据和菌株将存放在国家资料库，结果将通过出版物、专业会议报告和项目网站传播。将对本科生和研究生进行培训，学生将成为数据收集、分析和传播阶段的组成部分，并将鼓励学生在国家会议上发言。跨学院培训将加强研究生教育。这些pi将把这个项目的成果整合到他们所在院校的本科和研究生课程中，并将参加美国国家科学基金会主办的“K-16课堂中的科学探究”研讨会，以开发将结果与小学教育联系起来的方法。pi将利用与夏威夷科学院等当地外联团体的演讲和活动，通过指导、科学专题讨论会和中小学生的科学竞赛来鼓励科学理解。

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.