Dimensions: Collaborative research: Biological controls of the ocean C:N:P ratios

智力上的优点。海洋生物地球化学的基本模式之一是雷德菲尔德比率，它将表层浮游生物的化学计量与深海的化学联系起来。全球一致的C：N：P比106：16：1(Redfield比)没有明显的机制，特别是在不同海洋区域的浮游生物群落之间存在着巨大的元素差异。因此，了解生物多样性如何调节海洋的基本组成，对于理解海洋和气候作为一个整体--现在和未来--都是重要的。本研究的概念性假设如下：1.细胞的C：N：P比率受其广泛的分类群的限制，例如，它是否有外壳，它的大小，功能代谢，膜脂组成。在一个分类群中，有很高的遗传多样性。这些遗传多样性中的一些可能是横向转移的，或者可能在分类群内丢失，并赋予各种功能(有机磷同化、硝酸盐同化、光异质营养等)。功能多样性为细胞提供了进一步的灵活性，例如对不同的营养供应速率/比率做出反应的能力，并在分类群指定的范围内影响细胞的C：N：P比率。考虑到这些分类和遗传限制，细胞在生理上是可塑性的，并根据环境中的营养供应速率/比率改变其分配细胞资源的方式。表层海洋的微生物多样性(分类、遗传和功能)随时间和空间而变化，除了营养物质外，还受到许多因素的推动。这种混合物的总和构成了生态系统C：N：P，即雷德菲尔德所描述的比率。在这一框架的基础上，COPIS将对特定于分类群的化学计量学和生长率进行实地观察，进行基因组分析，并进行实验室化学恒化器实验，以加深对海洋分类、遗传和功能生物多样性如何控制表层海洋浮游生物化学计量学的理解。他们对这些数据的分析将导致对雷德菲尔德比在空间和时间上的变化的机械理解。这项研究将极大地扩展关于海洋微生物基因组多样性以及这种多样性如何影响生物地球化学的知识。海洋微生物的化学计量学是几乎每个化学或生物海洋学家都使用的参数，从将一种元素的测量值转换为另一种元素的测量值，到估计区域和全球的氮收支。这项研究对全球碳预算以及气候变化可能导致的任何变化也有重要影响。除了培训三名博士后学者和两名研究生外，还将建立Gateway导师计划，以招募从南加州地区社区大学转学的本科生(共12人)，培训他们，并为他们在研究型科学领域的职业生涯做好准备。该计划将包括广泛的指导，在UCI的研究经验，在基本输入输出系统，普林斯顿大学，或加州大学圣迭戈分校的实习机会，以及在全国会议上的演讲。这种密集的指导和研究经验为学生在科学领域的职业生涯做好了准备，并提高了对研究生学校的接受度。该计划将有很高比例的代表不足的群体，这反映在目标大学。为了了解浮游生物C：N：P比率的机械时空变异性，生物多样性不仅必须在传统的分类学水平上研究，而且必须在决定生物对其环境的反应的遗传和功能水平上进行研究。数据将被整合到一个综合的海洋生态、进化和生物地球化学模型中，具有灵活的化学计量学，包括细胞生化分配。用多种相互竞争的基因类型播种海洋的物理-生物耦合模型，能够探索资源获取和C：N：P比率的生态和进化模式。发展一种对生态学和进化过程的更机械性的研究，其中实验室和田间数据定义了不同生长和养分获取策略之间的权衡，将建立确定“进化趋同”的适应动力学框架。最后，将对照现场数据对模型结果进行评估。

Intellectual merit. One of the fundamental patterns of ocean biogeochemistry is the Redfield ratio, linking the stoichiometry of surface plankton with the chemistry of the deep ocean. There is no obvious mechanism for the globally consistent C:N:P ratio of 106:16:1 (Redfield ratio), especially as there is substantial elemental variation among plankton communities in different ocean regions. Thus, knowing how biodiversity regulates the elemental composition of the ocean is important for understanding the ocean and climate as a whole -- now and in the future. The conceptual hypotheses for this study are as follows:1. The C:N:P ratio of a cell is constrained by its broad taxonomic group, which determines, for example, whether it has an outer shell, its size, functional metabolism, membrane lipid composition.2. Within a taxon, there is high genetic diversity. Some of this genetic diversity is potentially laterally transferred, or can be lost within taxa, and confers various functional abilities (organic phosphate assimilation, nitrate assimilation, photoheterotrophy, etc.). Functional diversity provides the cell with further flexibility, such as the ability to respond to varying nutrient supply rates/ratios, and affects a cell's C:N:P ratio within the range specified by the taxon.3. Given these taxonomic and genetic constraints, a cell is physiologically plastic and modifies how it allocates cellular resources in response to nutrient supply rates/ratios in the environment.4. The microbial diversity (taxonomic, genetic, and functional) of the surface ocean varies over time and space, driven by many factors in addition to nutrients. The sum of this mixture composes the ecosystem C:N:P, the ratio that Redfield described. Based on this framework, the CoPIs will make field observations of taxon-specific stoichiometry and growth rates, genomic analyses, and conduct laboratory chemostat experiments to improve understanding of how ocean taxonomic, genetic, and functional biodiversity control the stoichiometry of the surface ocean plankton. Their analyses of these data would lead to a mechanistic understanding of variations in the Redfield ratio, both spatially and temporally.Broader impacts. This study will greatly expand knowledge of the genomic diversity among ocean microbes and how this diversity affects biogeochemistry. The stoichiometry of the ocean's microbes is a parameter that nearly every chemical or biological oceanographer uses, from converting measurements made in one element to another, to estimating regional and global nitrogen budgets. The research also has important implications for the global carbon budget and any changes that might result from climate change. Beyond training three postdoctoral scholars and two graduate students, a Gateway Mentoring Program will be established to recruit undergraduates (total of 12) transferring from community colleges in the Southern California area, training and preparing them for careers in research-oriented science. The program will consist of extensive mentoring, research experiences at UCI, internships at BIOS, Princeton, or UCSD, and presentations at national conferences. This intensive mentoring and research experience prepares students well for a career in science, and enhances acceptance to post-graduate schools. The Program will have a very high proportion of underrepresented groups as reflected in the targeted colleges.Integration. To understand mechanistically temporal and spatial variability of the plankton C:N:P ratio, biodiversity must be studied not only at the traditional taxonomic level, but at the genetic and functional levels which dictate organism response to their environment. Data will be integrated into a combined ocean ecological, evolutionary, and biogeochemical model, with flexible stoichiometry, including cellular biochemical allocations. Seeding a coupled physical-biological model of the oceans with multiple competing genotypes enables the exploration of ecological and evolutionary patterns of resource acquisition and C:N:P ratios. Developing a more mechanistic examination of the course of ecology and evolution, in which laboratory and field data define tradeoffs between different growth and nutrient acquisition strategies, would estabblish the framework of adaptive dynamics for determining "evolutionarily convergence". Finally, model outcomes will be evaluated against field data.