In swarms of flying insects, the motions of individuals are largely uncoordinated with those of their neighbours, unlike the highly ordered motion of bird flocks. However, it has been observed that insects may transiently form pairs with synchronized relative motion while moving through the swarm. The origin of this phenomenon remains an open question. In particular, it is not known if pairing is a new behavioural process or whether it is a natural by-product of typical swarming behaviour. Here, using an ‘adaptive-gravity’ model that proposes that insects interact via long-range gravity-like acoustic attractions that are modulated by the total background sound (via ‘adaptivity’ or fold-change detection) and that reproduces measured features of real swarms, we show that pair formation can indeed occur without the introduction of additional behavioural rules. In the model, pairs form robustly whenever two insects happen to move together from the centre of the swarm (where the background sound is high) towards the swarm periphery (where the background sound is low). Due to adaptivity, the attraction between the pair increases as the background sound decreases, thereby forming a bound state since their relative kinetic energy is smaller than their pair-potential energy. When the pair moves into regions of high background sound, however, the process is reversed and the pair may break up. Our results suggest that pairing should appear generally in biological systems with long-range attraction and adaptive sensing, such as during chemotaxis-driven cellular swarming.

中文翻译：

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由适应性长程相互作用驱动的昆虫群中的配对形成

在成群的飞虫中，个体的运动与其邻居的运动在很大程度上不协调，这与鸟群的高度有序运动不同。然而，已经观察到昆虫在穿过群体时可能会暂时形成具有同步相对运动的配对。这种现象的起源仍然是一个悬而未决的问题。特别是，目前尚不清楚配对是一种新的行为过程，还是典型的蜂群行为的自然副产品。在这里，使用“自适应重力”模型，该模型提出昆虫通过由总背景声音（通过“自适应”或折叠变化检测）调制的长距离重力式声学吸引力进行交互，并再现真实的测量特征。蜂拥而至，我们表明，在不引入额外的行为规则的情况下，结对确实可以发生。在模型中，只要两只昆虫碰巧从群的中心（背景声音高的地方）向群的外围（背景声音低的地方）一起移动，就会形成对。由于适应性，对之间的吸引力随着背景声音的减小而增加，从而形成束缚态，因为它们的相对动能小于它们的对势能。然而，当该对移动到高背景声音区域时，该过程相反，并且该对可能会破裂。我们的研究结果表明，配对通常出现在具有长距离吸引和自适应感知的生物系统中，例如在趋化性驱动的细胞群中。每当两只昆虫碰巧从群的中心（背景声音高的地方）向群的外围（背景声音低的地方）一起移动时，就会牢固地形成对。由于适应性，对之间的吸引力随着背景声音的减小而增加，从而形成束缚态，因为它们的相对动能小于它们的对势能。然而，当该对移动到高背景声音区域时，该过程相反，并且该对可能会破裂。我们的研究结果表明，配对通常出现在具有长距离吸引和自适应感知的生物系统中，例如在趋化性驱动的细胞群中。每当两只昆虫碰巧从群的中心（背景声音高的地方）向群的外围（背景声音低的地方）一起移动时，就会牢固地形成对。由于适应性，对之间的吸引力随着背景声音的减小而增加，从而形成束缚态，因为它们的相对动能小于它们的对势能。然而，当该对移动到高背景声音区域时，该过程相反，并且该对可能会破裂。我们的研究结果表明，配对通常出现在具有长距离吸引和自适应感知的生物系统中，例如在趋化性驱动的细胞群中。