IRCEB: Biological Stoichiometry from Genes to Ecosystems

9977047其他：IRC-EB计划旨在促进跨多个层次的生物组织和跨不同类型的栖息地和生物的综合研究。这样的工作应该能够阐明一些普遍的原则，从而开始重新统一本世纪产生的日益分散的生物知识财富。这个项目涉及一个多样化的研究团队，包括生理学家、微生物生态学家、理论生物学家、进化生物学家、湖泊学家和陆地生态系统生态学家。它涉及到从基因到生态系统、从微生物到后生动物、从湖泊到沙漠的明确的、概念上有组织的整合。该项目将使用生物化学计量学框架来评估生长所需的基本化学平衡如何将生物体的遗传学和生理学与生态系统动力学联系起来。生物化学计量学是研究生命系统中能量和多种化学元素平衡的学科。越来越多的研究表明，生物快速生长具有特征性的生物地球化学特征，体现在生物量C:N:P化学计量中，这是由快速生长与富P核糖体RNA的基本关联驱动的。此外，大量数据的积累表明，生物C:N:P化学计量是生态系统生态动力学的关键中介，包括营养动力学和生物地球化学循环。因此，似乎有机会利用化学计量学原理推导出具有重大生态意义的生长的遗传学和细胞生理学之间的因果关系。这个为期四年的项目将通过三个紧密交织的部分来尝试。在第一部分（有机体生物学）中，我们将研究一组生物（细菌、原生动物、真菌、昆虫、蠕虫）的生长、生化组成（RNA浓度）和C:N:P的耦合。C:N:P变化模式和生长模式将在这些分类群中相对于从研究得更好的群体中已知的模式进行评估。C:N:P组成不同的陆生和水生后生动物如何应对其需要量在化学计量上不平衡的食物资源。这些研究将检查动物对化学计量食品质量作出的行为和生理调整。组件2（进化）将考虑生物生长，C:N:P和生物化学分配在陆地（果蝇）和水生（水蚤）领域的进化背景下。这些表型特征以及与核糖体遗传学相关的关键基因型特征（如rDNA基因间间隔长度和基因剂量）如何在已知的系统发育树上排列将被研究。将对果蝇和水蚤进行生长速度的人工选择，并研究生长速度、C:N:P、RNA分配和核糖体基因型如何协同变化。在这些不同的选择制度结束时，将对每个分类单元的生理、行为和生态特征的选择结果进行评估。将确定生长- c:N:P耦合在允许多种资源限制下生态群落原位演化的理论研究中的意义。最后，第3部分将通过采样广泛的生态系统类型（湖泊、沙漠、草原、森林）的关键化学计量参数，在生态背景下考虑C:N:P的遗传学和生理学和生长。这些研究的主要目的是确定初级生产者和碎屑生物量的C:N:P化学计量是否与初级消费者生物量、C:N:P和多样性的特定模式有关。

9977047ElserThe IRC-EB Program seeks to promote research that integrates across multiple levels of biological organization and across diverse types of habitats and organisms. Such work should articulate general principles that can begin to re-unify the increasingly fragmented wealth of biological knowledge that this century has generated. This project involves a diverse team of researchers that includes a physiologist, a microbial ecologist, theoretical biologists, evolutionary biologists, limnologists, and a terrestrial ecosystem ecologist. It involves an explicit, conceptually organized, integration from genes to ecosystems, from microbes to metazoans, and from lakes to deserts. This project will use a framework of biological stoichiometry to assess how the fundamental chemical balance required for growth links the genetics and physiology of organisms to ecosystem dynamics. Biological stoichiometry is the study of the balance of energy and multiple chemical elements in living systems. Accumulating research suggests a characteristic biogeochemical signature of rapid organism growth, manifested in biomass C:N:P stoichiometry, which is driven by the fundamental association of rapid growth with P-rich ribosomal RNA. In addition, considerable data are accumulating that indicate that organism C:N:P stoichiometry is a key mediator of ecological dynamics, including trophic dynamics and biogeochemical cycling in ecosystems. Thus, there appears an opportunity to use principles of chemical stoichiometry to derive the causal connections between the genetics and cellular physiology of growth with major ecological implications. This 4-year project will make this attempt via three closely intertwined components. In Component 1 (Organismal Biology) the coupling of growth, biochemical composition (RNA concentration), and C:N:P will be examined in a suite of organisms whole nutritional physiology has not been well studies (bacteria, protozoa, fungi, insects, worms). Patterns of C:N:P variation and growth will be assessed in these taxa relative to patterns known from better-studied groups. How terrestrial and aquatic metazoan herbivores with contrasting C:N:P composition cope with food resources that are stoichiometrically imbalanced with respect to their requirements. These studies will examine both behavioral and physiological adjustments by animals in response to stoichiometric food quality. Component 2 (Evolution) will consider organism growth, C:N:P, and biochemical allocation in an evolutionary context in both terrestrial (Drosophila) and aquatic (Daphnia) realms. How these phenotypic traits, as well as key genotypic features associated with the genetics of the ribosome (such as rDNA intergenic spacer length and gene dosage) are arrayed on known phylogenetic trees will be investigated. Drosophila and Daphnia will be subjected to artificial selection on growth rate, and how growth rate, C:N:P, RNA allocation, and ribosomal genotypes change in concert will be examined. At the end of these divergent selection regimes, the consequences of selection for physiological, behavioral, and ecological features will be assessed for each taxon. The implication of growth-C:N:P coupling in theoretical studies that permit in situ evolution of ecological communities under multiple resource limitations will be determined. Finally, Component 3 will place considerations of genetics and physiology of C:N:P and growth in an ecological context by sampling a wide range of ecosystem types (lake, desert, grassland, forest) for key stoichiometric parameters. The main goal in these studies is to determine whether the C:N:P stoichiometry of primary producer and detritus biomass is associated with particular patterns of primary consumer biomass, C:N:P, and diversity.