Physical Aspects of Superorganism Physiology: Construction, Circulation, and Homeostasis in Fire Ant Colonies

生命历史上的重大转变发生在单个生物实体聚集在一起形成相互依赖的群体时，这些群体具有不同于个体的新特性。最近的这些转变发生在孤立的有机体结合在一起形成合作社会的时候。这种向社会性的转变尤其引人注目，因为许多不同的个人能够通过社会成员的协调行动作为一个单一的有机体行事。这种“超级生物”最好的例子就是群居昆虫。群居昆虫超级有机体呼吸、摄食、生长、繁殖和改变环境。尽管每个生命系统本身都很重要，但群体层面的平衡来自于所有系统的协调行动。这项研究计划的目的是发现在超有机体生理学中发挥重要作用的物理原理。超级生物监管原则将在信息和物理网络共存的系统中使用，例如在行人和车辆交通、城市和灾难景观以及神经和人工网络中。拟议中的研究也有助于解释为什么生物向社会性的转变如此成功。拟议中的研究将从“自上而下”的方法探索超有机体生理学的物理方面，以发现紧急的行为、生物力学和社会特征。这将由一种“自下而上”的方法加以补充，该方法将发现超有机体生理学的各个方面(外骨骼、循环系统的组织、愈合机制)如何依赖于土壤属性、蚂蚁形态、颗粒操纵生物力学和遗传学。本研究将以引进红火蚁--红火蚁-为模式生物系统进行的研究。火蚁拥有高度发达的社会制度，并共同完成复杂的任务。这项研究的目的是阐明管理超级有机体功能的原则和负责超级有机体稳定和成功的过程。具体地说，这个项目将研究类似于单个有机体的超级有机体的特征，包括：(1)超级有机体外骨骼的构建：这项研究将研究超级有机体如何从粘性颗粒介质中构建一个强大的外骨骼及其巢。这些过程将包括在不同介质中挖掘的生物力学、形成巢穴时的社会互动(如沟通、招募、工作量分配)和智能施工方法(例如，蚂蚁能否探测谷粒水平的应力)。(2)超生物循环：本研究将推导出受限空间的交通优化策略。这样的策略可以包括在空间和时间上分离工作任务，在巢空间中定位移动，组织信息枢纽，以及改变承运人的行为以应对繁忙的交通。(3)超有机体神经系统：这项研究将发现信息是如何通过个体之间的触觉互动在模式化的环境中传递的。所使用的方法将导致对超有机体神经和循环系统如何共存的理解。(4)巢穴物理特性的超有机体动态平衡：这项研究将确定超有机体对洪水引起的扰动、对巢网的机械侮辱、竞争物种的入侵以及火蚁物种杂交产生的遗传变异的反应。研究小组将利用女性小组成员的代表性来吸引女学生学习生物和物理之间的接口，这应该会吸引那些可能会对更成熟领域的障碍感到气馁的学生。研究小组还将通过动手和DIY活动、与公共教育俱乐部的合作以及科学与娱乐业的整合来探索公众参与的战略。

Major transitions in the history of life occurred when individual biological entities came together to form interdependent groups with emergent properties that differed from the individuals. The most recent of these transitions occurred when solitary organisms joined together to form cooperative societies. This transition to sociality has been particularly remarkable because many distinct individuals are able to behave as a single organism through the coordinated actions of society members. The best examples of such "superorganisms" are colonies of social insects. Social insect super-organisms breathe, feed, grow, breed and modify their environments. Although each life system is important on its own, the balance at the colony level arises from coordinated action of all systems. The purpose of this research program is to discover physical principles that play important roles in super-organism physiology. Super-organism regulatory principles will be of use in systems where information and physical networks coexist, such as in pedestrian and vehicle traffic, urban and disaster landscapes, and neural and artificial networks. The proposed studies could also help explain why the biological transition to sociality has been so successful.The proposed studies will probe physical aspects of super-organism physiology from a "top-down" approach to discover emergent behavioral, biomechanical, and social features. This will be complemented by a "bottom-up" approach that will discover how aspects of super-organism physiology (exoskeleton, organization of circulatory system, healing mechanisms) depend on soil properties, ant morphology, grain manipulation biomechanics, and genetics. This research will be conducted using the red imported fire ant, Solenopsis invicta, as a model super-organism system. Fire ants possess highly developed social systems and work together to complete complex tasks. The goal of this research is to elucidate principles governing the functioning of the super-organism and the processes responsible for super-organism stability and success. Specifically, this program will study super-organism features that are analogous to those in single organisms including: (1) Super-organism exoskeleton construction: this research will investigate processes by which the super-organism constructs a robust exoskeleton, its nest, from cohesive granular media. Such processes will include biomechanics of excavation in different media, social interactions upon nest formation (like communication, recruitment, workload distribution) and intelligent construction methods (e.g. can ants probe grain level stresses). (2) Super-organism circulation: This research will deduce traffic optimization strategies in confined spaces. Such strategies may include separation of work tasks in space and time, localization of movement in nest space, organization of information hubs, and modification of the carrier's behavior in response to heavy traffic. (3) Super-organism nervous system: This research will discover how information is transmitted through a patterned environment through tactile interactions of individuals. The approaches used will lead to an understanding of how the superorganism nervous and circulatory systems co-exist. (4) Super-organism homeostasis of physical properties of the nest: This research will determine the response of the super-organism to perturbations arising from flooding, mechanical insults to nest networks, invasion of competitive species, and genetic variation derived from hybridization of fire ant species. The research team will leverage the representation of female group members to attract female students to study of the interface between biology and physics, which should attract students who might be discouraged by the barriers in more established fields. The research team will also explore strategies of public involvement through hands-on and DIY initiatives, collaboration with public education clubs and integration of science with the entertainment industry.