The fecundity/longevity trade-off in a clonal ant

在许多独居生物中，由于资源的权衡，寿命与繁殖力呈负相关。群居昆虫女王是这条规则的一个明显例外。生殖个体似乎避免甚至逆转了这一基本权衡：他们延长了寿命，并具有高产卵能力。然而，在大多数高级群居昆虫中，繁殖体和非繁殖体在个体发育、形态、生理、行为和资源可获得性方面存在巨大差异，这可能会影响繁殖力和寿命之间的相互关系。因此，克隆蚂蚁，如斑点扁尾蚂蚁，是研究没有这些混淆特征的权衡的合适模型：克隆蚂蚁的繁殖体和非繁殖体几乎是相同的。在第一个资助阶段，我们记录了许多影响寿命和繁殖力的因素，例如营养操作(脂肪含量和蛋白质与碳水化合物的比例)、去掉鸡蛋和氧化应激。此外，复制体和非复制体之间的转录组分析匹配了这些先前的结果，并揭示了几个已知的基因，这些基因对氧化应激做出反应，参与营养信号通路，与新陈代谢有关，或将环境刺激与表型变化联系起来。总体而言，我们的结果表明，营养以及IIS/TOR途径在调节繁殖力和寿命方面发挥了重要的中介作用。尽管这些途径之间的几个相互作用是已知的，但基因之间的许多“联系”以及它们如何对这种明显的权衡进行重塑仍不清楚。在第二个资助阶段，我们现在的主要目标是更深入地了解这些相互关系，以及生殖和饮食如何影响寿命和基因表达变化。为此，我们将操纵(I)繁殖成本，(Ii)饮食，和(Iii)通过RNAi参与繁殖/寿命权衡的假定基因。之后，我们将测量这些操作对寿命、繁殖力、氧化应激和免疫反应的影响。最后，基于最有希望的治疗方法，我们将通过转录组研究来比较基因和途径修饰。我们的项目将允许我们，通过直接操纵候选基因并在表型水平上测试它们的效果，来阐明它们在权衡中的作用。它还将很好地补充研究单位2281内的其他项目，使我们能够比较不同模式生物之间涉及的途径，并概括关于群居昆虫繁殖和寿命调节的假设。

In many solitary organisms longevity is negatively correlated with fecundity because of resource trade-offs. Queens of social insects are a notable exception to this rule. Reproductive individuals appear to avoid or even reverse this fundamental trade-off: they have extended longevity and high egg-laying capacities. However, in most advanced social insects, reproductives and non-reproductives differ tremendously in ontogeny, morphology, physiology, behavior and resource availability, which may affect the interrelation between fecundity and longevity. Clonal ants, such as Platythyrea punctata, are therefore suitable models to study the trade-off without these confounding traits: reproductives and non-reproductives of clonal ants are mostly identical. Nevertheless, reproductives live significantly longer than all non-egg-laying workers.During the 1st funding phase, we documented a number of factors that influence longevity and fecundity, e.g., nutritional manipulations (fat content and protein to carbohydrate ratios), removal of eggs, and oxidative stress. In addition, a transcriptome analysis - between reproductives and non-reproductives - matched these previous results and revealed several genes that are known to respond to oxidative stress, to be involved in nutrient signalling pathways, related to metabolism, or link environmental stimuli with phenotypic changes. Overall, our results point to the role of nutrition as well as to IIS/TOR pathways as important mediators in the regulation of fecundity and longevity. Although several interactions among these pathways are known, many “connections” among genes and how they contribute to this apparent remolding of the trade-off remain unclear. In the 2nd funding phase, our main aim is now to gain a deeper understanding of these interrelations and how reproduction and diet affect lifespan and gene expression changes. To do so, we will manipulate (i) the costs of reproduction, (ii) diets, and (iii) putative genes involved in the fecundity/longevity trade-off via RNAi. Thereafter we will measure the consequences of these manipulations for longevity, fecundity, oxidative stress, and immune responses. Finally, based on the most promising treatments, we will compare via transcriptome studies gene and pathway modifications. Our project will allow us, by manipulating (in-)directly candidate genes and by testing their effect at a phenotypic level, to elucidate their roles in the trade-off. It will also complement well other projects within the Research Unit 2281 by allowing us to compare the pathways involved between the different model organisms and to generalize hypotheses about the regulation of reproduction and longevity in social insects.