IRCEB: Biological Stoichiometry from Genes to Ecosystems

9977047Elser IRC-EB计划旨在促进跨生物组织的多个层次和不同类型的栖息地和生物体的整合研究。这项工作应阐明一般原则，以便开始重新统一本世纪产生的日益分散的生物学知识财富。该项目涉及一个多元化的研究团队，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，湖沼学家和陆地生态系统生态学家。它涉及一个明确的，概念上有组织的，从基因到生态系统，从微生物到后生动物，从湖泊到沙漠的整合。该项目将使用生物化学计量学的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态联系起来。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科学。积累的研究表明，生物体快速生长的特征生物化学特征，表现在生物量C：N：P化学计量，这是由快速生长与富含P的核糖体RNA的基本关联驱动的。此外，大量数据的积累表明，生物体C：N：P化学计量是生态动态（包括生态系统中的营养动态和生物地球化学循环）的关键介体。因此，似乎有机会利用化学计量学原理来推导出具有重大生态影响的遗传学和生长细胞生理学之间的因果关系。这个为期4年的项目将通过三个紧密交织的组成部分进行尝试。在组件1（有机生物学）中，将在一系列尚未充分研究的有机体（细菌，原生动物，真菌，昆虫，蠕虫）中检查生长，生化组成（RNA浓度）和C：N：P的耦合。模式的C：N：P的变化和增长将在这些类群相对于已知的模式，从更好的研究组进行评估。陆生和水生后生动物食草动物与对比C：N：P组成如何应对食物资源，化学计量不平衡，他们的要求。这些研究将检查动物对化学计量食物质量的行为和生理调整。组件2（进化）将考虑生物生长，C：N：P，和生化分配在陆地（果蝇）和水生（水蚤）领域的进化背景。这些表型性状以及与核糖体遗传学相关的关键基因型特征（如rDNA基因间间隔区长度和基因剂量）如何排列在已知的系统发育树上将被研究。将对果蝇和水蚤的生长速率进行人工选择，并将检查生长速率、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，生理，行为和生态功能的选择的后果将被评估为每个taxon.The影响的生长-C：N：P耦合在理论研究，允许在多个资源限制下的生态群落的原位进化将被确定。最后，第3部分将通过对各种生态系统类型（湖泊、沙漠、草原、森林）进行取样，以获得关键的化学计量参数，从而在生态背景下考虑C：N：P的遗传学和生理学以及生长。这些研究的主要目标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相关。

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.