Data from: Gut microbiota of dung beetles correspond to dietary specializations of adults and larvae

Vertebrate dung is central to the dung beetle life cycle, constituting food for adults and a protective and nutritive refuge for their offspring. Adult dung beetles have soft mandibles and feed primarily on nutritionally rich dung particles, while larvae have sclerotized mandibles and consume coarser dung particles with a higher C/N ratio. Here, using the dung beetles Euoniticellus intermedius and E. triangulatus, we show that these morphological adaptations in mandibular structure are also correlated with differences in basic gut structure and gut bacterial communities between dung beetle life stages. Metagenome functional predictions based on 16S rDNA characterization further indicated that larval gut communities are enriched in genes involved in cellulose degradation and nitrogen fixation compared to adult guts. Larval gut communities are more similar to female gut communities than they are to those of males, and bacteria present in maternally provisioned brood balls and maternal ‘gifts’ (secretions deposited in the brood ball along with the egg) are also more similar to larval gut communities than to those of males. Maternal secretions and maternally provisioned brood balls, as well as dung, were important factors shaping the larval gut community. Differences between gut microbiota in the adults and larvae are likely to contribute to differences in nutrient assimilation from ingested dung at different life history stages.脊椎动物粪便对于蜣螂的生命周期而言是核心资源，既是成虫的食物来源，同时也为其后代提供兼具保护性与营养性的栖息场所。成年蜣螂拥有柔软的颚部，主要取食营养丰富的粪便颗粒；而幼虫则具有骨化的颚部，可摄食碳氮比更高的较粗粪便颗粒。本研究以中间蜣螂（Euoniticellus intermedius）和三角蜣螂（E. triangulatus）为实验材料，证实了颚部结构的这类形态学适应性变化，同时与蜣螂不同生命周期阶段的肠道基础结构及肠道细菌群落差异存在显著关联。基于16S核糖体核糖核酸（16S rDNA）测序表征的宏基因组功能预测进一步显示，相较于成虫肠道菌群，幼虫肠道菌群中富集了与纤维素降解、固氮作用相关的功能基因。幼虫肠道菌群与雌性蜣螂肠道菌群的相似性，显著高于其与雄性蜣螂肠道菌群的相似性；而母体提供的育幼球及母源性“馈赠物”（即与卵一同被沉积于育幼球内的分泌物）中所含的细菌，与幼虫肠道菌群的相似性也高于其与雄性肠道菌群的相似性。母源性分泌物、母体提供的育幼球以及粪便，均是塑造幼虫肠道菌群群落的关键影响因子。成虫与幼虫肠道微生物群的差异，可能会导致不同生命周期阶段中，宿主对摄入粪便的营养吸收效率存在差异。