The fecundity/longevity trade-off in a clonal ant

在许多独居生物中，由于资源权衡，寿命与繁殖力呈负相关。群居昆虫的女王是这条规则的一个明显的例外。生殖个体似乎避免甚至逆转了这种基本的权衡：它们的寿命更长，产卵能力也更强。然而，在大多数先进的社会昆虫中，生殖动物和非生殖动物在个体发育、形态、生理、行为和资源可利用性方面存在巨大差异，这可能会影响繁殖力与寿命之间的相互关系。因此，无性系蚂蚁，如Platythyrea punctata，是研究权衡的合适模型，没有这些混淆的特征：无性系蚂蚁的生殖和非生殖大部分是相同的。然而，生殖动物的寿命明显长于所有不产卵的工蜂。在第一个资助阶段，我们记录了一些影响寿命和繁殖力的因素，例如营养操纵（脂肪含量和蛋白质与碳水化合物的比例）、去除鸡蛋和氧化应激。此外，在生殖动物和非生殖动物之间进行的转录组分析与这些先前的结果相匹配，并揭示了一些已知对氧化应激作出反应的基因，这些基因参与营养信号通路，与代谢有关，或将环境刺激与表型变化联系起来。总的来说，我们的研究结果表明，营养以及IIS/TOR通路在调节繁殖力和寿命方面发挥了重要的调节作用。虽然这些途径之间的一些相互作用是已知的，但基因之间的许多“联系”以及它们如何促成这种明显的权衡重塑仍不清楚。在第二个资助阶段，我们的主要目标是深入了解这些相互关系，以及繁殖和饮食如何影响寿命和基因表达变化。为此，我们将通过RNAi操纵(i)繁殖成本，（ii）饮食，以及（iii）与繁殖力/寿命权衡有关的假定基因。此后，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进行基因和途径修饰的比较。我们的项目将允许我们，通过操纵（in-）直接候选基因，并通过在表型水平上测试它们的影响，来阐明它们在权衡中的作用。它还将很好地补充2281研究单位内的其他项目，使我们能够比较不同模式生物之间所涉及的途径，并概括有关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.