Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS - Université de Tours, Tours, France.
J Evol Biol. 2021 Jul;34(7):1034-1045. doi: 10.1111/jeb.13791. Epub 2021 May 3.
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.
动物肠道内的微生物常常通过改变宿主的生理、生殖和行为功能来提高自身适应性。虽然最近的研究表明，它们还可能塑造宿主的社交行为，从而对动物社会进化产生关键影响，但肠道微生物群对母性行为的影响仍未得到探索。这令人惊讶，因为这种行为在动物中广泛存在，通常决定着幼体和父母双方的适应性，并且是复杂动物社会进化的关键。在这里，我们测试了广谱抗生素利福平是否会改变耳虫的肠道微生物群，从而损害其孵化前和孵化后的母性行为。我们的研究结果首先证实，利福平改变了母亲的肠道微生物群落，并表明在进行卵护理之前和之后，肠道微生物群的组成存在差异。然而，与我们的预测相反，利福平诱导的肠道微生物群改变并没有改变孵化前或孵化后的护理行为。独立于母性行为，利福平增加了雌性的粪便产生量，导致卵和幼体变轻。相比之下，利福平并未改变在雌性 300 天生命周期内测量的 21 个其他生理、生殖和寿命特征中的任何一个。总的来说，这些发现表明，用利福平等广谱抗生素改变肠道微生物群并不一定会影响宿主的社交性。它们还强调，并非所有动物都与它们的微生物群形成了相互依存关系，并且在推广肠道微生物在宿主生物学中的核心作用时需要谨慎。
