Causes and consequences of inter-individual variability in social insects

社会群体中的动物在行为反应上往往表现出一致的差异。这种可变性是如何产生的？它对群体的集体属性有什么影响？我将以群居昆虫为模型系统，详细阐述这些迷人的问题。我将在过去几年中建立的熊蜂群体中使用温度调节作为实验系统。在这个项目中，我有四个紧密相连的主要目标，从一个殖民地的工人之间的行为差异的基本机制，到这种个体间变异的最终后果。每一个实验都从一个新的角度来看待与我们理解集体行为和自组织有关的问题。(1)一个潜在的重要的和很少探索的机制，个体间的社会昆虫的变异是preimaginal经验。环境波动，例如幼虫发育期间的温度，可能是表型变异的来源。第一步，我将建立大黄蜂育雏自然暴露的温度范围。利用这些温度，我将在不同的稳定或波动的温度下饲养幼蜂，然后观察成年蜜蜂在其殖民地和幼蜂假人实验室中的行为。最后，我将暴露育雏的性（皇后和雄蜂）不同的温度，让他们建立殖民地，并分析其育雏的温度调节行为可能的表观遗传效应。(2)造成工人行为差异的第二个重要机制是经验。我将解决经验的作用，特别是任务效率和经验对个人的任务专业化的体温调节大黄蜂。人们通常认为，分工导致高效率的专家，然而，很少有实证研究记录了经验对效率的影响，或效率对经验的影响，甚至更少的研究存在于觅食以外的任务，其中行为的效率与某种直接奖励没有直接关系。(3)最终，个体间的变异性被认为是劳动分工，群体灵活性和群体适应性的关键特征。然而，一个直接的测试的影响个体间的行为变异的健身相关的集体特质仍然缺乏。我将实验性地操纵和直接测量一组大黄蜂工人的集体能力，稳态调节育雏温度的温度反应行为的个体间变异的影响。(4)最后，在这些实验中获得的所有结果将被用来改进现有的自组织模型，并测试新的假设的重要性，个体间的变异对自组织集体反应的昆虫群体。

Animals in social groups often show consistent differences in their behavioural responses. How does this variability arise; and what effects does it have on collective properties of the group? I will address these fascinating questions in detail, using social insects as model system. I will use thermoregulation in colonies of bumblebees as experimental systems that I have well established over the past years. In this project, I have four main objectives that are tightly interconnected and reach from the proximate mechanisms underlying the behavioural differences among the workers of a colony to the ultimate consequences of such inter-individual variability. Each experiment takes a novel perspective on questions relevant for our understanding of collective behaviour and self-organization. (1) One potentially important and little explored mechanism underlying interindividual variability in social insects is preimaginal experience. Environmental fluctuations in e.g. temperature during larval development may be a source of phenotypic variation. In a first step, I will establish the range of temperatures that bumblebee brood is naturally exposed to. Using these temperatures, I will then raise brood (pupae) under different stable or fluctuating temperatures and later observe the behaviour of the adult bees both within their colonies and in an experimental chamber on a brood dummy. Finally, I will expose brood of sexuals (queens and drones) to different temperatures, let them establish colonies, and analyze the thermoregulative behaviour of their brood for possible epigenetic effects.(2) A second important mechanism underlying the behavioural differentiation of workers is experience. I will address the role of experience, specifically of task efficiency and experience on individual task specialization of thermoregulating bumblebees. It is commonly assumed that division of labour leads to highly efficient specialists, however, few empirical studies have documented the effect of experience on efficiency, or of efficiency on experience, and even less studies exist on tasks besides foraging, where the efficiency of a behaviour is not directly correlated to some kind of direct reward. (3) Ultimately, interindividual variability is considered a key feature for division of labour, colony flexibility and colony fitness. However, a direct test of the effect of interindividual behavioural variability on a fitness relevant collective trait is still lacking. I will experimentally manipulate and directly measure the impact of interindividual variability in temperature response behaviour within a group of bumblebee workers on their collective ability to homeostatically regulate brood temperature.(4) Finally, all results obtained in theses experiments will be used to improve existing self-organization models and to test new hypotheses about the importance of interindividual variability on self-organized collective responses of an insect colony.