Behavioral and mechanical determinants of collective subsurface nest excavation
Behavioral and mechanical determinants of collective subsurface nest excavation
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DOI：
10.1242/jeb.113795
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发表时间：
2015-05-01
影响因子：
2.8
通讯作者：
Goldman, Daniel I.
中科院分区：
文献类型：
--
作者：
Monaenkova, Daria;Gravish, Nick;Goldman, Daniel I.
拓扑复杂结构的集体建构是社会行为的胜利之一。例如，许多蚂蚁建造由隧道和腔室网络组成的地下巢穴。这些“超级有机体”的挖掘取决于基质操纵的生物力学、个体的相互作用以及媒介的稳定性和凝聚力。为了发现稳健社会挖掘的原理，我们使用x射线计算机断层扫描来监测由火蚁群（Solenopsis invicta）在由二氧化硅颗粒组成的实验室基质中建造的巢穴的三维生长，操纵两种基质特性：粒径和重量水分含量。除了完全干燥或完全饱和的基质外，蚂蚁能够在所有基质中筑巢；对于给定的粒度，巢体积相对不敏感的水分含量。在中等含水率下，隧道最深，最大隧道深度与对小棒状侵入物的屈服力（粘结力的代表）相关。这意味着增加的内聚强度允许建造抗扰动的隧道，但不会降低单个开挖能力。蚂蚁使用两种不同的行为来制造由湿颗粒组成的颗粒，这取决于基质的成分。然而，尽管能够在更有凝聚力的基质中制造更大的稳定颗粒，但颗粒大小在所有条件下都是相似的。我们假设这种颗粒大小平衡了个人的承载能力与携带颗粒通过狭窄拥挤的隧道的需要。我们的结论是，通过个体复杂的挖掘行为，可以在多种基质中有效地挖掘相似形状的巢穴，这些行为可以适应不同的基质特性和集体工作的需要。
Collective construction of topologically complex structures is one of the triumphs of social behavior. For example, many ant species construct underground nests composed of networks of tunnels and chambers. Excavation by these 'superorganisms' depends on the biomechanics of substrate manipulation, the interaction of individuals, and media stability and cohesiveness. To discover principles of robust social excavation, we used X-ray computed tomography to monitor the growth in three dimensions of nests built by groups of fire ants (Solenopsis invicta) in laboratory substrates composed of silica particles, manipulating two substrate properties: particle size and gravimetric moisture content. Ants were capable of nest construction in all substrates tested other than completely dry or fully saturated; for a given particle size, nest volume was relatively insensitive to moisture content. Tunnels were deepest at intermediate moisture content and the maximum tunnel depth correlated with measured yield force on small rod-shaped intruders (a proxy for cohesive strength). This implies that increased cohesive strength allowed creation of tunnels that were resistant to perturbation but did not decrease individual excavation ability. Ants used two distinct behaviors to create pellets composed of wetted particles, depending on substrate composition. However, despite the ability to create larger stable pellets in more cohesive substrates, pellet sizes were similar across all conditions. We posit that this pellet size balances the individual's load-carrying ability with the need to carry this pellet through confined crowded tunnels. We conclude that effective excavation of similarly shaped nests can occur in a diversity of substrates through sophisticated digging behaviors by individuals which accommodate both differing substrate properties and the need to work within the collective.