Abstract

Ant colonies are self-organized systems, meaning that complex collective behavior emerges from local interactions among colony members without any central control. Self-organized systems are sensitive to initial conditions, whereby small random effects are amplified through positive feedback and have a large influence on collective outcomes. This sensitivity has been well demonstrated in collective decision-making by ants that use mass recruitment via trail pheromones, where it is attributed to the highly nonlinear relationship between the amount of pheromone on a trail and its effectiveness at attracting recruits. This feature is absent in many species, such as the rock ant Temnothorax rugatulus (Emery) whose tandem run recruitment shows a linear relationship between effort and effectiveness. Thus, these ants may have other behavioral responses that amplify initial differences during collective choices. We investigated this by testing whether nest site selection is influenced by small differences in the amount of brood at competing sites. Our results show that T. rugatulus colonies prefer a nest containing brood items to an empty nest, even when the brood-containing nest has only one brood item. When both nests have brood, colonies prefer the nest that contains more. However, as the numbers of brood items becomes more similar, this preference becomes weaker. Moreover, the smaller the difference in brood number, the more likely are colonies to split between sites. We discuss potential behavioral mechanisms for the observed effect, as well as its implications for number sense in ants.

中文翻译：

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Temnothorax rugatulus（膜翅目：蚁科）中育雏数量对巢址选择的影响

摘要

蚁群是自组织系统，这意味着复杂的集体行为来自蚁群成员之间的局部互动，没有任何中央控制。自组织系统对初始条件很敏感，因此小的随机效应通过正反馈被放大，并对集体结果产生很大影响。这种敏感性在蚂蚁通过跟踪信息素进行大规模招募的集体决策中得到了很好的证明，这归因于跟踪信息素的数量与其吸引新兵的有效性之间的高度非线性关系。这种特征在许多物种中不存在，例如岩蚁Temnothorax rugatulus(Emery) 的串联招聘显示了努力和有效性之间的线性关系。因此，这些蚂蚁可能有其他行为反应，这些反应会放大集体选择期间的初始差异。我们通过测试巢址选择是否受竞争地点育雏量的微小差异影响来对此进行调查。我们的结果表明，T. rugatulus与空巢相比，殖民地更喜欢包含育雏物品的巢穴，即使包含育雏的巢穴只有一个育雏物品。当两个巢都有育雏时，殖民地更喜欢包含更多的巢。然而，随着育雏项目的数量变得更加相似，这种偏好变得更弱。此外，育雏数量的差异越小，菌落在不同地点之间分裂的可能性就越大。我们讨论了观察到的效应的潜在行为机制，以及它对蚂蚁数感的影响。