Data from: Fitness Costs of Worker Specialisation for Ant Societies

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialisation affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialisation in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialisation is disadvantageous for a colony’s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialisation than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.劳动分工对社会群体的存续至关重要，但目前学界对个体特化如何影响群体整体适合度（fitness）仍知之甚少。尽管特化型工蚁在其所负责的任务上相较于泛化型工蚁效率更高，但它们也可能缺乏应对任务需求快速变化的灵活性。当社会群体面临动态且不可预测的事件时，这种僵化性可能会带来适合度成本——例如受到社会性寄生蓄奴蚁的攻击。本研究通过实验评估了受美国蓄奴蚁（T. americanus）攻击的长刺盘胸蚁（Temnothorax longispinosus）的行为特化对其群体水平适合度的影响。研究团队基于全部3842只工蚁的行为反应，对102个长刺盘胸蚁群体的社会组织结构进行了人工调控。研究结果显示，在蓄奴蚁突袭期间，严格的行为特化对蚁群的年度繁殖与种群增长均不利。这类适合度成本可能会促使动态环境中的蚁群选择泛化型策略；本研究同时证实，野外中暴露于蓄奴蚁威胁的蚁群，其特化程度相较于未受蓄奴蚁侵扰的种群更低。本研究结果为泛化型个体的普遍存在提供了一种解释，并凸显了其对整个社会群体的灵活性与功能鲁棒性（robustness）的重要意义。