Folivorous flying squirrels are among the smallest arboreal mammals, reaching the limit of metabolic demands subsisting on a low quality diet (e.g. leaves) that the flying squirrels recruit suites of gut microbes to digest throughout their evolution history. Yet, even among flying squirrel species (ca. 40 species), their body sizes differ by several folds posting drastic difference in mass-specific metabolic rates and dietary niche. Therefore we studied flying squirrels of three genera, Petaurista (1500 g), Trogopterus (300g) and Pteromys (150g) and expect to see different gut microbiota that may link to efficiency in digesting plant fibers. We analyzed the fecal samples from 6 Petaurista, 4 Trogopterus and 19 Pteromys with 16S rRNA gene amplicon of the V3-V4 region and NGS. 160 and 510 OTUs were discovered in Petaurista and Pteromys, respectively. We used PICRUSt to predict the molecular functions of gut microbiota in each hosts based on the 16S rRNA data. The diversity and predicted functions data of gut microbiota may suggest the relationship among gut microbiota, the dietary niche and habitats of their host.
Gut microbiota are distinct in three genera. The most distinct feature of the differences lies in the bacterial phylum Firmicutes which are over 95% in Petaurista and only 80% in Pteromys. Firmicutes are considered more abundant in obese mice to gain higher mass-specific metabolic rates. It is generally considered that mammals below the mass range 0.9-1.7 kg are near the lowest mass margin a species can be strictly folivorous. Petaurista is strictly folivorous while Pteromys take more rich food such as fruits and nuts. Therefore, it appears that the strictly folivorous Petaurista might have recruited more Firmicutes to sustain primarily on leave. We also discussed the metabolic features in the bacterial phyla and weather of habitats that may contribute to the mass-specific metabolic rates and dietary niche of the three genera of flying squirrels. The result shows that gut microbiota of Pteromys response in seasonal temperature changes. Most predicted genes/enzymes which involved in the pathway of starch and sucrose metabolism were presented in all gut microbiota of flying squirrels. These cellulose metabolism gene counts of Petaurista’s gut microbiota were more abundant than the other two small flying squirrels'.