# Two Species of Long-Day Breeding Hamsters Exhibit Distinct Gut Microbial Responses to Photoperiodic Variations

## TL;DR

This study shows that two types of hamsters respond differently to changes in daylight length in terms of their gut microbes, suggesting species-specific adaptations.

## Contribution

The study reveals distinct gut microbial responses to photoperiod in two long-day breeding hamster species.

## Key findings

- Striped hamsters showed no change in gut microbial diversity under different photoperiods.
- Djungarian hamsters exhibited lower microbial diversity and significant shifts in bacterial composition under long daylight conditions.
- Photoperiod affected microbial network complexity and potential functions differently in the two species.

## Abstract

The regulatory role of photoperiod on animals is crucial, and its connection with the gut microbial communities is now receiving increasing attention. The aim of this study was to investigate whether the gut microbiota of animals with similar light-regulated life history traits exhibit consistent responses to the photoperiod. Through laboratory lighting control experiments, we found that two species of long-day breeding rodents, striped hamsters (Cricetulus barabensis) and Djungarian hamsters (Phodopus sungorus), exhibited distinct gut microbial responses in diversity, bacterial composition and potential functional features to the photoperiodic variations. This further implies that there may be distinct variations in the role played by the gut microbiota of different animals in assisting the host in adapting to environmental changes.

The relationship between the gut microbiota and photoperiod has received widespread attention, and it is necessary to explore the probable common mechanisms involved. We tested whether the gut microbiota of animals with similar light-regulated life history traits would also exhibit consistent responses to the photoperiod. Here, two species of long-day breeders, striped hamsters (Cricetulus barabensis) and Djungarian hamsters (Phodopus sungorus), were raised under different photoperiods (long daylight, LD; short daylight, SD), and their cecal contents were collected to assess the gut microbiota. There was no difference in the gut microbial diversity between the groups of striped hamsters; however, in the Djungarian hamsters, lower Chao and Shannon indices were observed in the LD group than in the SD group. The bacterial community variation in the striped hamsters was reflected mainly in the enrichment of the genera Enterorhabdus and Jeotgalicoccus in the LD group; meanwhile, more taxa with significant changes in relative abundance under different photoperiods were found in the Djungarian hamsters, such as the enrichment of the genera Lactobacillus and Faecalibaculum in the LD group and the enrichment of the genera Ruminococcus and Colidextribacter in the SD group. The LD conditions substantially reduced the complexity of the gut microbial network in the Djungarian hamsters and increased the R2 value of the striped hamster gut microbiota under fitting with a neutral community model. Moreover, the potential gut microbial functions in the striped hamsters were relatively stable, but variations were observed in multiple pathways between the groups of Djungarian hamsters. These results contribute to the understanding of host species specificity in the response of the gut microbiota to external changes.