Abstract Task partitioning allows for efficient coordination of behavior in social insect colonies. Many task allocation studies focus on social insect species with discrete morphological worker subcastes, such as those possessing major and minor workers with strongly differentiated body plans. Much less is known about task partitioning among size-variable workers lacking discrete morphological subcastes. We investigated task fidelity and its correlation with worker size in Formica species with differing degrees of body size variation. During a mark-recapture study that focused on three worker tasks (honeydew collection, nest building, and protein foraging) across 2 days, 98.6% of 3570 recaptured workers exhibited task fidelity. In species with high levels of worker size variation, worker size is strongly correlated with task performance. This size-task correlation is weaker, but still present, in species with less variably sized workers. Our results suggest that Formica use size-based task partitioning, a form of morphological polyethism. We expect social insects with and without discrete morphological worker subcastes to differ in ontogeny, evolutionary history, and degree of behavioral flexibility. Identifying the scope of variation in task partitioning mechanisms will facilitate comparative studies, thereby elucidating evolutionary histories and outcomes of alternative strategies. Significance statement Division of labor is thought to increase the efficiency and success of animal societies by allowing the performance of multiple tasks in parallel, rather than sequentially. We investigated the task partitioning strategy employed by an ecologically dominant ant genus characterized by continuous worker size variation but lacking discrete morphological worker subcastes. We show that several species employ a form of morphological polyethism, wherein individuals specialize in tasks according to body size. Size-mediated morphological polyethism in the absence of discrete morphological worker subcastes has been demonstrated in a few other social insects. However, this task allocation strategy is likely more common than previously recognized, as most insect societies display natural worker size variation. Further, we argue that it is important to distinguish between size- and subcaste-based morphological polyethism. Alternative task partitioning strategies are likely to impact animal societies’ resilience to environmental perturbations, which are becoming increasingly common in the face of global change.

中文翻译：

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缺乏离散形态工人亚种姓的蚂蚁中的任务划分

摘要 任务划分允许有效协调社会昆虫群体中的行为。许多任务分配研究侧重于具有离散形态工人亚种姓的社会昆虫物种，例如那些拥有具有强烈差异化身体计划的主要和次要工人的社会昆虫物种。对于缺乏离散形态亚种姓的大小可变的工人之间的任务划分知之甚少。我们调查了具有不同体型变化程度的福米卡物种的任务保真度及其与工人体型的相关性。在一项为期 2 天的专注于三项工人任务（蜜露采集、筑巢和蛋白质觅食）的标记重新捕获研究中，3570 名重新捕获的工人中有 98.6% 表现出任务保真度。在具有高水平工人尺寸变化的物种中，工人尺寸与任务表现密切相关。这种大小与任务的相关性较弱，但在工人大小可变的物种中仍然存在。我们的结果表明 Formica 使用基于大小的任务划分，这是一种形态多民族主义。我们预计具有和不具有离散形态工人亚种姓的社会昆虫在个体发育、进化历史和行为灵活性程度上有所不同。确定任务划分机制的变异范围将有助于比较研究，从而阐明替代策略的进化历史和结果。意义声明 分工被认为通过允许并行而不是顺序执行多项任务来提高动物社会的效率和成功。我们研究了一种生态优势蚂蚁属采用的任务划分策略，其特征是工人尺寸连续变化但缺乏离散形态工人亚种姓。我们展示了几个物种采用了一种形态多伦理，其中个体根据体型专门从事任务。在没有离散形态工人亚种姓的情况下，尺寸介导的形态多伦理已经在其他一些社会昆虫中得到证实。然而，这种任务分配策略可能比以前认识到的更常见，因为大多数昆虫社会表现出自然工人的大小变化。此外，我们认为区分基于大小和亚种姓的形态多伦理主义很重要。