Causes and consequences of inter-individual variability in social insects

社会群体中的动物通常在行为反应上表现出一致的差异。这种可变性是如何产生的？它对集团的集体财产有什么影响？我将使用群居昆虫作为模型系统，详细解决这些有趣的问题。我将使用大黄蜂群体的体温调节作为我在过去几年中很好地建立的实验系统。在这个项目中，我有四个紧密相连的主要目标，从一个群体中工人行为差异的基本机制到这种个体间差异的最终后果。每个实验都对与我们理解集体行为和自我组织相关的问题采取了新的视角。(1)群居昆虫个体间变异的一个潜在的重要机制是前想象经验，但很少有人研究。幼虫发育期间的环境波动，例如温度，可能是表型变异的一个来源。在第一步中，我将确定大黄蜂幼崽自然暴露的温度范围。使用这些温度，然后我将在不同的稳定或波动的温度下饲养幼蜂(蛹)，然后观察成年蜜蜂在它们的群体中和在试验室中对孵化假人的行为。最后，我将把一窝性伴侣(蜂王和雄蜂)暴露在不同的温度下，让它们建立蜂群，并分析它们后代的体温调节行为，以寻找可能的表观遗传影响。(2)工作者行为差异的第二个重要机制是经验。我将讨论经验的作用，特别是任务效率和经验对温度调节大黄蜂个体任务专业化的作用。人们通常认为，分工会产生高效率的专家，然而，很少有实证研究证明经验对效率的影响，或者效率对经验的影响，除了觅食之外，关于任务的研究就更少了，在这些任务中，一种行为的效率与某种直接奖励没有直接关系。(3)归根结底，个体间的变异性被认为是劳动分工、群体灵活性和群体适合度的关键特征。然而，对个体间行为差异对与健康相关的集体特征的影响的直接测试仍然缺乏。我将在实验中操纵和直接测量一组大黄蜂工蜂内部温度反应行为的个体间变异性对他们集体自我平衡调节孵化温度的能力的影响。(4)最后，这些实验中获得的所有结果将用于改进现有的自组织模型，并测试关于个体间变异性对昆虫群体自组织集体反应的重要性的新假设。

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.