Shukla Shantanu P, Sanders Jon G, Byrne Marcus J, Pierce Naomi E
Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, 02138, MA, USA.
School of Animal, Plant, and Environmental Sciences, University of Witwatersrand, Wits, 2050, South Africa.
Mol Ecol. 2016 Dec;25(24):6092-6106. doi: 10.1111/mec.13901. Epub 2016 Nov 20.
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.
脊椎动物的粪便对蜣螂的生命周期至关重要，是成虫的食物来源，也是其后代的保护和营养庇护所。成年蜣螂的下颚柔软，主要以营养丰富的粪便颗粒为食，而幼虫的下颚则硬化，以碳氮比更高的较粗粪便颗粒为食。在这里，我们以中间真蜣螂和三角真蜣螂为研究对象，发现下颚结构的这些形态学适应也与蜣螂不同生命阶段的基本肠道结构和肠道细菌群落差异相关。基于16S rDNA特征的宏基因组功能预测进一步表明，与成虫肠道相比，幼虫肠道群落中参与纤维素降解和固氮的基因更为丰富。幼虫肠道群落与雌性肠道群落的相似性高于与雄性肠道群落的相似性，而且在母体提供的育幼球和母体“礼物”（与卵一起沉积在育幼球中的分泌物）中存在的细菌与幼虫肠道群落的相似性也高于与雄性肠道群落的相似性。母体分泌物、母体提供的育幼球以及粪便都是塑造幼虫肠道群落的重要因素。成虫和幼虫肠道微生物群的差异可能导致不同生命史阶段从摄入的粪便中吸收营养的差异。
