Natural foraging selection and gut microecology of two subterranean rodents from the Eurasian Steppe in China

As the most abundant group of mammals, rodents possess a very rich ecotype, which makes them ideal for studying the relationship between diet and host gut microecology. Zokors are specialized herbivorous rodents adapted to living underground. Unlike more generalized herbivorous rodents, they feed on the underground parts of grassland plants. There are two species of the genus Myospalax in the Eurasian steppes in China: one is Myospalax psilurus , which inhabits meadow grasslands and forest edge areas, and the other is M. aspalax , which inhabits typical grassland areas. How are the dietary choices of the two species adapted to long-term subterranean life, and what is the relationship of this diet with gut microbes? Are there unique indicator genera for their gut microbial communities? Relevant factors such as the ability of both species to degrade cellulose are not yet clear. In this study, we analysed the gut bacterial communities and diet composition of two species of zokors using 16S amplicon technology combined with macro-barcoding technology. We found that the diversity of gut microbial bacterial communities in M. psilurus was significantly higher than that in M. aspalax and that the two species of zokors possessed different gut bacterial indicator genera. Based on the results of Mantel analyses, the gut bacterial community of M. aspalax showed a significant positive correlation with the creeping-rooted type food, and there was a complementary relationship between the axis root type food and the rhizome type food dominated (containing bulb types and tuberous root types) food groups. Functional prediction based on KEGG found that M. psilurus possessed a stronger degradation ability in the same cellulose degradation pathway. Neutral modelling results showed that the gut flora of the M. psilurus has a wider ecological niche compared to that of the M. aspalax . This provides a new perspective for understanding how rodents living underground in grassland areas respond to changes in food conditions.