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个体生物实体聚集在一起形成相互依存的群体时，这些群体具有不同于个体的涌现特性。最近的这些转变发生在独居生物联合起来形成合作社会的时候。这种向社会性的转变尤其引人注目，因为许多不同的个体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“超级有机体”的最好例子是群居昆虫的群体。群居昆虫的超级有机体呼吸、觅食、生长、繁殖和改变它们的环境。虽然每个生命系统本身都很重要，但群体层面的平衡源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起重要作用的物理原理。超有机体调节原理将用于信息和物理网络共存的系统，例如行人和车辆交通，城市和灾害景观，以及神经和人工网络。拟议的研究也可以帮助解释为什么生物向社会性的转变如此成功。提出的研究将从“自上而下”的方法探索超级有机体生理学的物理方面，以发现紧急行为，生物力学和社会特征。这将辅以一种“自下而上”的方法，该方法将发现超级有机体生理学（外骨骼、循环系统的组织、愈合机制）的各个方面如何依赖于土壤特性、蚂蚁形态、颗粒操纵生物力学和遗传学。本研究将以红火蚁（Solenopsis invicta）为模型超生物系统进行。火蚁拥有高度发达的社会系统，它们会合作完成复杂的任务。本研究的目的是阐明控制超级有机体功能的原则，以及负责超级有机体稳定和成功的过程。具体来说，该项目将研究类似于单个生物的超级生物特征，包括：(1)超级生物外骨骼结构：本研究将研究超级生物从粘性颗粒介质中构建坚固外骨骼（巢）的过程。这些过程将包括在不同媒介中挖掘的生物力学，筑巢时的社会互动（如沟通，招募，工作量分配）和智能建造方法（例如蚂蚁可以探测颗粒水平的应力）。(2)超生物循环：本研究将推导出有限空间内的交通优化策略。这些策略可能包括在空间和时间上分离工作任务、在巢空间中定位运动、组织信息中心以及改变载体的行为以应对繁忙的交通。(3)超生物神经系统：该研究将揭示信息是如何通过个体的触觉相互作用在有图案的环境中传递的。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)蚁巢物理特性的超级有机体动态平衡：本研究将确定超级有机体对洪水、对蚁巢网络的机械损伤、竞争物种入侵以及火蚁杂交产生的遗传变异等扰动的反应。研究小组将利用女性成员的代表性，吸引女性学生来研究生物学和物理学之间的界面，这将吸引那些可能因更成熟的领域的障碍而气馁的学生。研究小组亦会探讨市民参与的策略，包括亲身参与和DIY活动、与公众教育俱乐部合作，以及将科学与娱乐行业结合。

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.