Holland Jacob G, Nakayama Shinnosuke, Porfiri Maurizio, Nov Oded, Bloch Guy
Department of Ecology, Evolution & Behaviour, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Department of Mechanical and Aerospace Engineering, New York University Tandon School of Engineering, Brooklyn, NY 11201, USA.
Insects. 2021 Mar 10;12(3):236. doi: 10.3390/insects12030236.
Specialisation and plasticity are important for many forms of collective behaviour, but the interplay between these factors is little understood. In insect societies, workers are often developmentally primed to specialise in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of labour. Workers may also plastically switch between tasks or vary their effort. The degree to which developmentally primed specialisation limits plasticity is not clear and has not been systematically tested in ecologically relevant contexts. We addressed this question in 20 free-foraging bumble bee () colonies by continually manipulating colonies to contain either a typically diverse, or a reduced ("homogeneous"), worker body size distribution while keeping the same mean body size, over two trials. Pooling both trials, diverse colonies produced a larger comb mass, an index of colony performance. The link between body size and task was further corroborated by the finding that foragers were larger than nurses even in homogeneous colonies with a very narrow body size range. However, the overall effect of size diversity stemmed mostly from one trial. In the other trial, homogeneous and diverse colonies showed comparable performance. By comparing behavioural profiles based on several thousand observations of individuals, we found evidence that workers in homogeneous colonies in this trial rescued colony performance by plastically increasing behavioural specialisation and/or individual effort, compared to same-sized individuals in diverse colonies. Our results are consistent with a benefit to colonies of large and small specialists under certain conditions, but also suggest that plasticity or effort can compensate for reduced (size-related) specialisation. Thus, we suggest that an intricate interplay between specialisation and plasticity is functionally adaptive in bumble bee colonies.
专业化和可塑性对多种形式的集体行为都很重要，但这些因素之间的相互作用却鲜为人知。在昆虫社会中，工蚁通常在发育过程中就被设定好专门从事不同的任务，有时还会有形态或生理上的适应性变化，以促进劳动分工。工蚁也可能灵活地在任务之间切换或调整其努力程度。发育引发的专业化对可塑性的限制程度尚不清楚，也未在与生态相关的背景下进行系统测试。我们通过持续操控20个自由觅食的熊蜂群落来解决这个问题，在两个试验中，使群落要么拥有典型的多样化工蚁体型分布，要么拥有减少的（“同质化”）工蚁体型分布，同时保持相同的平均体型。综合两个试验来看，多样化的群落产生了更大的巢脾质量，这是群落表现的一个指标。体型与任务之间的联系进一步得到了证实，即即使在体型范围非常窄的同质化群落中，觅食者也比护理者体型更大。然而，体型多样性的总体影响主要源于一个试验。在另一个试验中，同质化和多样化的群落表现相当。通过基于对数千个个体的观察来比较行为特征，我们发现有证据表明，在这个试验中，同质化群落中的工蚁通过灵活增加行为专业化和/或个体努力来挽救群落表现，相比之下，多样化群落中体型相同的个体则不然。我们的结果与在某些条件下大小不同的专家型个体对群落有益的观点一致，但也表明可塑性或努力可以弥补减少的（与体型相关的）专业化。因此，我们认为专业化和可塑性之间复杂的相互作用在熊蜂群落中具有功能适应性。
