# Age-Specific Composition and Predicted Function of Gut Microbiota in Plateau Pikas (Ochotona curzoniae)

## TL;DR

This study explores how gut microbes in plateau pikas change with age, finding similar overall microbial communities but differences in specific functions like cellulose degradation.

## Contribution

The study is the first to investigate age-related changes in gut microbiota composition and predicted functions in plateau pikas.

## Key findings

- Gut microbial composition and diversity were similar between adult and juvenile plateau pikas.
- Juveniles showed lower abundance of cellulose-degrading bacteria, suggesting a preference for low-fiber diets.
- Three KEGG level 2 metabolic pathways differed significantly between age groups.

## Abstract

The community of microbes living in the gut is essential for an animal’s health, helping with digestion and adapting to its environment. For the plateau pika, a small mammal native to the high-altitude Qinghai–Tibet Plateau, we wanted to understand if these gut microbes change as the animal ages. During growth and development, the diversity and composition of intestinal microbiota change. Understanding the impact of age on gut microbiota is crucial for further ecological research and conservation management. We compared the gut microbes of adult and juvenile pikas using metagenomic sequencing. We found that the overall types of microbes and predicted functions were very similar between adults and juveniles. However, the changes in the proportion of cellulose-degradation-related bacterial communities in juveniles suggest that they tend to choose low-fiber diets. There were three metabolic pathways with significant differences in the KEGG secondary metabolic pathways. This study, however, had limitations that constrained the generalizability of the results. In the future, more in-depth studies are needed to verify the observed trends and clarify the main drivers of age-related microbial variation in wild herbivores.

Gut microbes play a crucial role in regulating physiological processes such as host energy metabolism, nutrient absorption, and environmental adaptation. The predicted functions of gut microbes can be influenced by many factors, both extrinsic and intrinsic to the hosts. The plateau pika is a key species in the alpine ecosystem of the Qinghai–Tibet Plateau. Previous research on the plateau pika primarily examined how extrinsic factors affected its gut microbiota. However, studies on intrinsic factors are scarce. Here, we used live-trapping to capture plateau pikas and collect cecum contents. Using metagenomic sequencing of cecum content samples, we characterized and compared the gut microbial composition and predicted function of plateau pika in adult (n = 9) and juvenile (n = 9) populations. The results indicated that Bacillota and Bacteroidete were the major bacterial phyla. The core gut microbial genera were the same, but the relative abundance of Oscillospira in juveniles was significantly lower than that in adults. The changes in the proportion of cellulose-degradation-related bacterial communities in juveniles suggest that they tend to choose low-fiber diets. In this study, we found no significant differences in the gut microbial composition and diversity, KEGG level 1 metabolic pathways, or CAZy class level between adult and juvenile plateau pikas. In total, the composition and predicted functions of cecal microorganisms in juvenile and adult male plateau pikas were not different. Regarding KEGG level 2 metabolic pathways, the juvenile group had a higher relative abundance of metabolic pathways for cofactors and vitamins, terpenoids, and polyketides, whereas the adult group had a higher relative abundance of energy metabolism. However, the resulting differences remain unclear. Therefore, future research should validate the above findings on a broader spatio-temporal scale and conduct cross-species comparisons to construct a microbial ecological framework for the health management of plateau wild animals.