The microbes residing within the gut of an animal host often increase their own fitness by modifying their host's physiological, reproductive and behavioural functions. Whereas recent studies suggest that they may also shape host sociality and therefore have critical effects on animal social evolution, the impact of the gut microbiota on maternal care remains unexplored. This is surprising, as this behaviour is widespread among animals, often determines the fitness of both juveniles and parents, and is essential in the evolution of complex animal societies. Here, we tested whether life-long alterations of the gut microbiota with rifampicin-a broad-spectrum antibiotic-impair pre- and post-hatching maternal care in the European earwig. Our results first confirm that rifampicin altered the mothers' gut microbial communities and indicate that the composition of the gut microbiota differs before and after egg care. Contrary to our predictions, however, the rifampicin-induced alterations of the gut microbiota did not modify pre- or post-hatching care. Independent of maternal care, rifampicin increased the females' faeces production and resulted in lighter eggs and juveniles. By contrast, rifampicin altered none of the other 21 physiological, reproductive and longevity traits measured over the 300 days of a female's lifetime. Overall, these findings reveal that altering the gut microbiota with a large spectrum antibiotic such as rifampicin does not necessarily affect host sociality. They also emphasize that not all animals have evolved a co-dependence with their microbiota and call for caution when generalizing the central role of gut microbes in host biology.

中文翻译：

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用广谱抗生素改变肠道微生物群不会损害欧洲螟的产妇护理。

动物宿主肠道内的微生物通常会通过改变宿主的生理、生殖和行为功能来提高自身的健康度。尽管最近的研究表明它们也可能塑造宿主的社会性，因此对动物的社会进化具有重要影响，但肠道微生物群对母体护理的影响仍未得到探索。这是令人惊讶的，因为这种行为在动物中很普遍，通常决定了幼鱼和父母的适应性，并且在复杂动物社会的进化中至关重要。在这里，我们测试了使用利福平（一种广谱抗生素）对肠道微生物群的终生改变是否会损害欧洲螟的孵化前和孵化后的母体护理。我们的结果首先证实利福平改变了母亲的 肠道微生物群落，并表明肠道微生物群的组成在鸡蛋护理前后不同。然而，与我们的预测相反，利福平引起的肠道微生物群的改变并没有改变孵化前或孵化后的护理。独立于母体护理，利福平增加了雌性的粪便产量，并导致鸡蛋和幼鱼变轻。相比之下，利福平没有改变女性一生 300 天的其他 21 项生理、生殖和长寿特征。总体而言，这些发现表明，用大谱抗生素（如利福平）改变肠道微生物群并不一定会影响宿主的社会性。