Reversal of the fecundity / longevity trade-off across social transitions in ants

研究群居昆虫繁殖力/寿命权衡的逆转，将为调节衰老提供重要的见解。到目前为止，研究还没有在整个社会昆虫中找到共同的衰老分子调控因素，可能是因为典型研究物种之间不受控制的生态差异涵盖了调节衰老的关键因素。我们建议通过以蚂蚁为重点的比较方法来解决这个问题，以确定与任何模式物种的特定生态或系统发育位置无关的衰老调节因素。我们研究单位第一阶段资助的理论工作预测，社会昆虫工作者的任何生殖潜力都应该选择更长的预期寿命。在大多数蚂蚁物种中，工蚁可以产生单倍体雄性蚂蚁。它们通常在女王去世时这样做，以获得直接的健康。然而，工蚁通常不能完全取代女王，因为他们缺乏产生二倍体女王和工蚁的能力。有趣的是，两种不同的工蚁类型在蚂蚁身上反复进化：一种是全能的工蚁，可以同时产生雄性和雌性；另一种是不育的工蚁，无法产生任何可存活的后代。除了这些生理限制外，工蚁直接繁殖的机会还取决于群体水平的生活史参数，如群体大小和蜂王数量，这些参数应该会进一步影响工蚁的衰老机制。我们将调查种姓(工蚁或女王)、繁殖力(产卵与否)和年龄(年轻或年老)如何影响15种蚂蚁的基因表达。我们仔细选择了不同种群大小和蜂王数量的物种，以量化工蚁繁殖潜力对衰老的影响，与物种的生态和系统发育地位无关。延长许多物种寿命的两个因素是对氧化应激和病原体暴露的抵抗力。有人提出，群居昆虫女王活得更长，是因为工作人员保护它们免受这些环境压力的影响，和/或为它们提供足够的资源，以维持更长时间的主动修复和防御机制。在拟议的项目中，我们将通过实验研究不同繁殖潜力(跨15个物种和15个物种内)的蚂蚁工作者对氧化应激和免疫挑战的抵抗力是否也不同。从野外收集蚂蚁并在实验室进行实验的工作量需要三名经验丰富的蚂蚁研究人员的联合力量和专业知识。总体而言，这项跨越15个蚂蚁物种的比较项目将提供关于蚂蚁衰老的分子和生理机制的有价值的信息，繁殖力如何与蚁后和工蚁的寿命联系在一起，以及我们对高级社会进化转型背景下繁殖力/寿命权衡的逆转的一般理解。

Investigating the reversal of the fecundity/longevity trade-off in social insects will provide important insights into the modulation of senescence. So far, studies have failed to find common molecular regulators of ageing across the social insects, possibly because uncontrolled ecological variation between the typical study species has covered key factors regulating ageing. We propose to tackle this problem by using a comparative approach focussed on ants, to identify senescence regulators that are independent of any model species' specific ecology or phylogenetic position.Theoretical work from the 1st funding phase of our research unit predicts that any reproductive potential of social insect workers should select for longer life expectancy. In most ant species, workers can produce haploid males. They usually do so when the queen dies, to gain direct fitness. However, workers typically cannot fully replace the queen because they lack the ability to produce diploid queens and workers. Interestingly, two alternative worker types have evolved repeatedly in ants: totipotent workers that can produce both males and females, and sterile workers that cannot produce any viable offspring. In addition to these physiological constraints, a worker's chance for direct reproduction also depends on colony-level life-history parameters, such as colony size and queen number, which should further affect worker ageing mechanisms.We will investigate how caste (queen or worker), fecundity (egg-laying or not), and age (young or old) affect gene expression in 15 species of ants. We carefully selected species with varying colony size and queen number, to quantify the effect of worker reproductive potential on senescence independent of the species' ecology and phylogenetic position. Two factors that prolong lives in many species are the resilience to oxidative stress and pathogen exposure. It has been proposed that social insect queens live longer because workers protect them against these environmental stressors and/or provide them with enough resources to maintain active repair and defence mechanisms for a longer time. In the proposed project, we will experimentally investigate whether ant workers with different reproductive potential (across and within 15 species) also differ in their resilience to oxidative stress and immune challenge.The workload of collecting the ants from the field and conducting the experiments in the laboratory will require the combined force and expertise of three experienced ant researchers. Overall, this comparative project across 15 ant species will provide valuable information on the molecular and physiological mechanisms underlying ageing in ants, how fecundity is linked to longevity in both queens and workers, and our general understanding of the reversal of the fecundity/longevity trade-off on the background of transitions in advanced social evolution.