Group Size, Scaling of Work, and Metabolism in Ant Colonies

每克消耗的能量随着体型的增加而降低的模式(称为新陈代谢比例)在所有动物群体中都会发生，但其背后的机制仍不清楚。有趣的是，群居昆虫群体的新陈代谢水平随着群体大小的增加而降低。这个项目将结合实验和数学模型来确定蚂蚁群体中能源使用和工作组织之间的关系。蚁群是这个问题的典范，因为它们高度协调的社会是围绕维持蚁群生长和维护所需的工作组织起来的，类似于生物体的新陈代谢过程。了解代谢伸缩的机制在生理学、医学和农业中具有潜在的应用价值。这个项目中的基于能量的模型和实验将远远超出社会昆虫群体的范围，包括为人类种群规模问题提供信息。该项目将把这项研究与数学和社会生物学共同指导计划联系起来，以培训本科生研究团队一起学习生物和数学。学生将参加关于社会生物学原理和模拟建模的正式培训计划，然后以跨学科团队的形式参与合作研究。与亚利桑那州立大学研究和少数族裔项目的现有联系将被用来招收代表不足的学生加入该项目。关于群体规模、社会行为和新陈代谢的在线K-12使用的教学模块也将与亚利桑那州立大学的生物学家外展项目合作开发。这个项目由综合组织系统分部的动物行为计划、数学科学分部的数学生物学计划和生物、数学和物理科学交界处的BIOMAPS计划共同资助。群体规模是社会性的最基本属性之一，对社会组织和健康具有重要影响。以前的工作发现，较大的收割机蚂蚁群(Pogonomyrmex CalforNicus)在任务表现和活动模式方面表现出异速生长变化，包括工人专业化程度的提高。此外，他们还转移了精力的分配，可能是从更昂贵的任务中转移出来。与此潜在地结合在一起，菌落也显示出一致的低速代谢比例模式，这与生物体的比例模式相匹配。由于任务绩效与菌群的生长和新陈代谢直接相关，这些结果导致了这样的假设，即较大的菌群通过调整工作组织的变化来实现能源使用的规模经济。为了检验群体大小如何影响工作组织，将在不同大小的实验室群体中测量工作人员在不同任务间的分布、个人任务专门化和工作人员活动水平。将同时测量群体新陈代谢、孵化产量和生长率，以将行为组织与群体新陈代谢结果联系起来。此外，还将评估群体人口统计数据，包括工人规模和年龄分布，以确定它们对新陈代谢变化的贡献。这些参数将被测量：(A)大小不同但年龄不变的群体；(B)个体遗传学上大小随时间变化的群体；(C)大小操纵的群体。实证研究将与模拟、微分方程和优化模型相结合，以询问任务组织和活动的组成部分如何相互作用，以产生菌落新陈代谢和生产力的比例变化。

The pattern of lower energy use per gram with increasing size (known as metabolic scaling) occurs across all animal groups, yet the mechanisms behind it are still not understood. Intriguingly, social insect colonies show the same level of reduced metabolism with increasing colony size. This project will combine experiments and mathematical models to determine the relationships between energy use and the organization of work in ant colonies. Ant colonies serve as an exemplar for this question, because their highly coordinated societies are organized around the work needed to sustain colony growth and maintenance, analogous to metabolic processes in organisms. Understanding the mechanisms underlying metabolic scaling has potential applications in physiology, medicine, and agriculture. The energy-based models and experiments in this project will be relevant well beyond social insect colonies, including informing human population scaling issues. The project will connect this research with a Mathematics and Social Biology Co-mentoring Program, to train research teams of undergraduates together in biology and mathematics. Students will participate in a formal training program on social biological principles and simulation modeling, and then participate as cross-disciplinary teams in collaborative research. Existing connections with research and minority programs at ASU will be used to recruit under-represented students into the program. Teaching modules on group size, social behavior, and metabolism for online K-12 use will also be developed in collaboration with ASU's Ask-a-Biologist outreach program. This project is co-funded by the Animal Behavior program in the Division of Integrative Organismal Systems, the Mathematical Biology program in the Division of Mathematical Sciences, and the BIOMAPS program for proposals at the interface of Biology, Math and the Physical Sciences.Group size is one of the most fundamental attributes of sociality, with important effects on social organization and fitness. Previous work has found that larger harvester ant colonies (Pogonomyrmex californicus) exhibit allometric changes in task performance and activity patterns, including increased worker specialization. They additionally shift the allocation of effort, possibly away from more expensive tasks. Potentially coupled with this, colonies also show a consistent pattern of hypometric metabolic scaling, which matches that of organismal scaling patterns. Because task performance is directly linked to colony growth and metabolism, these results lead to the hypothesis that larger colonies achieve economies of scale in energy use from scaling changes in the organization of work. To examine how colony size influences work organization, the distribution of workers across tasks, individual task specialization, and worker activity levels will be measured in laboratory colonies of varying size. Colony metabolism, brood production and growth rates will be measured simultaneously to link behavioral organization to colony metabolic consequences. Additionally, colony demographics, including worker size and age distributions, will be assessed for their contributions to variation in metabolism. These parameters will be measured for: (a) colonies that vary in size but not age; (b) colonies changing in size ontogenetically over time; (c) size-manipulated colonies. The empirical research will be combined with simulation, differential equation and optimization models to ask how components of task organization and activity might interact to generate scaling changes in colony metabolism and productivity.