Collaborative Research: Nutritional physiology of life history allocation trade-offs

生命史特征，如寿命、分散和总生殖产出是关键的有机体适应。许多生活史性状彼此负耦合，因为分配给一个性状（如产蛋）的营养物质不能用于另一个性状（如生产用于扩散的脂质燃料）。权衡的大小可能受到生物体可用营养物质的数量和质量的强烈影响，但目前对营养物质投入如何影响生活史权衡知之甚少。在这里，我们用一种翅膀多态蟋蟀Gryllus firmus来研究这个问题。这种蟋蟀存在于两种基因指定的形式中，一种适应飞行（分散），以牺牲产卵为代价，另一种适应以分散为代价最大化繁殖（它缺乏飞行肌肉）。使用一系列明确定义的饮食，它们的蛋白质-碳水化合物组成（和总热量含量）不同，将进行比较，揭示这两种不同的表型如何在其特定生活史中不同地提取、相互转换和消除所需的蛋白质和碳水化合物。具体而言，本研究将测量蛋白质和碳水化合物在身体组织中的消耗和同化，记录这两种营养素如何分配到飞行和生殖器官，并使用放射性示踪剂和生化途径的酶学研究来研究这两种营养素的相互转化和代谢消除。一个重要的焦点将是确定允许特定表型在不断变化的营养环境中获得/产生（其生活史）所需的生物分子的生理机制。结果将适用于广泛的生物体，包括人类的生活史特征（例如寿命）。这个项目也有一个重要的教学组成部分，包括培养博士后，为本科生提供研究机会，为中学教育工作者开设讲习班，为教授进化论的基本原理提供新方法。

Life history traits such as longevity, dispersal and total reproductive output are key organismal adaptations. Many life history traits are negatively coupled with each other because nutrients allocated towards one trait (e.g. egg production) are not available for another trait (e.g. production of lipid fuel for dispersal). The magnitude of trade-offs can be strongly influenced by the amount and quality of nutrients available to an organism, but currently little is known about how nutrient inputs affect life history trade-offs. Here this issue is investigated using a wing-polymorphic cricket, Gryllus firmus. This cricket exists as one of two genetically-specified forms, one adapted for flight (dispersal) at the expense of egg production, the other adapted to maximize reproduction at the expense of dispersal (it lacks flight muscle). Using a range of well-defined diets that differ in their protein-carbohydrate composition (and total caloric content), a comparison will be made that reveals how these two contrasting phenotypes differentially extract, interconvert, and eliminate protein and carbohydrate demanded by their specific life history. Specifically, this study will measure consumption and assimilation of protein and carbohydrates into body tissues, document how these two nutrients are allocated to flight and reproduction organs, and use radiotracer and enzymological studies of biochemical pathways to study interconversion and metabolic elimination of these two nutrients. An important focus will be identifying the physiological mechanisms that allow a particular phenotype to acquire/produce the biomolecules it needs (for its life history) in a constantly shifting nutritional environment. Results will be applicable to a wide range of organisms, including life history traits (e.g. longevity) in humans. This project also has a significant instructional component, including the training of a postdoctoral associate, research opportunities for undergraduate students, and the development of workshops for secondary school educators which provides novel approaches to teaching basic principles of evolution.