Many animals live in groups and engage in collective actions which can enhance their fitness. One common example is collective decision-making, which mainly arises from social interactions that modify the individual behaviour. Despite the widespread interest in animal personalities on the one hand and in social effects (such as social organisation, social learning or anti-predator behaviour) on the other, the question of how the amount of among-individual differences, coupled with social interactions, influence group cohesion has rarely been addressed. For this purpose, I used a modelling approach based on aggregation behaviour of cockroaches to explore the mechanisms underlying such context-dependent behaviour. The results of simulations considering different degrees (none, medium, high) of personality variation in a non-social and social context were compared to experimental patterns of aggregation dynamics in cockroaches. The comparison between the simulated and experimental data show that only a model that considers differences in individuals was able to reproduce the experimental patterns of individuals and groups. In addition, the comparison between models suggest that some individuals may play a keystone role during aggregation dynamics, influencing the behaviour of others and facilitating the collective decision. Finally, I show that personality variation amplifies the effects of social inter-attractions, thus increasing the speed of aggregation, shedding light on the mechanisms underpinning social modification of individual behaviour.

中文翻译：

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性格变异改善了蟑螂的集体决策

许多动物群居并参与集体活动，这可以增强它们的健康。一个常见的例子是集体决策，它主要来自改变个人行为的社会互动。尽管一方面对动物的个性和另一方面对社会影响（如社会组织、社会学习或反捕食者行为）的广泛兴趣，个体间差异的数量以及社会互动如何，影响群体凝聚力很少被提及。为此，我使用了一种基于蟑螂聚集行为的建模方法来探索这种依赖于环境的行为背后的机制。考虑不同程度（无、中、高）在非社会和社会背景下的人格变异与蟑螂聚集动力学的实验模式进行了比较。模拟数据和实验数据的对比表明，只有考虑个体差异的模型才能再现个体和群体的实验模式。此外，模型之间的比较表明，一些个体可能在聚合动态过程中发挥关键作用，影响他人的行为并促进集体决策。最后，我展示了人格变异会放大社会相互吸引的影响，从而提高聚合速度，揭示支持个人行为社会改变的机制。模拟数据和实验数据的对比表明，只有考虑个体差异的模型才能再现个体和群体的实验模式。此外，模型之间的比较表明，一些个体可能在聚合动态过程中发挥关键作用，影响他人的行为并促进集体决策。最后，我展示了人格变异会放大社会相互吸引的影响，从而提高聚合速度，揭示支持个人行为社会改变的机制。模拟数据和实验数据的对比表明，只有考虑个体差异的模型才能再现个体和群体的实验模式。此外，模型之间的比较表明，一些个体可能在聚合动态过程中发挥关键作用，影响他人的行为并促进集体决策。最后，我展示了人格变异会放大社会相互吸引的影响，从而提高聚合速度，揭示支持个人行为社会改变的机制。模型之间的比较表明，一些个人可能在聚合动态过程中发挥关键作用，影响他人的行为并促进集体决策。最后，我展示了人格变异会放大社会相互吸引的影响，从而提高聚合速度，揭示支持个人行为社会改变的机制。模型之间的比较表明，一些个人可能在聚合动态过程中发挥关键作用，影响他人的行为并促进集体决策。最后，我展示了人格变异会放大社会相互吸引的影响，从而提高聚合速度，揭示支持个人行为社会改变的机制。