Changes in the community structure of the symbiotic microbes of wild amphibians from the eastern edge of the Tibetan Plateau

Liang Liang Xu,Mengjie Zhang,Jianping Jiang,Qing Chang,Youhua Chen,Hua Chen,Wei Zhu,Lifeng Zhu,Guoqing Lu

doi:10.1002/mbo3.1004

Abstract

Environment has a potential effect on the animal symbiotic microbiome. Here, to study the potential relationship of the symbiotic microbiomes of wild amphibians with altitude, we collected the gut and skin samples from frogs (nine species) and the environmental samples (water and soil samples) from the Leshan Mountains (altitude: 360–410 m) and Gongga Mountains (altitude: 3340–3989 m) on the eastern edge of the Tibetan Plateau. Bufo gargarizans (Bg) samples were collected from both the Leshan and Gongga mountain regions (Bg was the only species sampled on both mountains). The DNA extracted from each sample was performed high‐throughput sequencing (MiSeq) of bacterial 16S rRNA gene amplicons. High relative abundance of Caulobacteraceae and Sphingomonadaceae was found in skin samples from both Bg and the other high‐altitude amphibians (nine species combined). High relative abundance of Coxiellaceae and Mycoplasmataceae was found in gut samples from both Bg and the other high‐altitude amphibians. Furthermore, the alpha and beta diversities of skin and gut samples from Bg and the other amphibian species (nine species combined) were similar. In terms of the symbiotic microbial community, the low‐altitude samples were less diverse and more similar to each other than the high‐altitude samples were. We speculated that extreme high‐altitude environments and host phylogeny may affect the amphibian microbiome. Despite the distinct microbial community differences between the skin and gut microbiomes, some functions were similar in the Bg and combined high‐altitude samples. The Bg and high‐altitude skin samples had higher oxidative stress tolerance and biofilm formation than the low‐altitude skin samples. However, the opposite results were observed for the Bg and high‐altitude gut samples. Further study is required to determine whether these characteristics favor high‐altitude amphibian adaptation to extreme environments.

Highlights

Symbiotic microbes play important roles in host disease immunity (Hooper, Dan, & Macpherson, 2012) and environmental adaptation (Lavrinienko, Tukalenko, Mappes, & Watts, 2018)
On the basis of the microbial data derived from high-throughput sequencing of the bacterial 16S rRNA gene in the gut and skin samples, we asked the following three questions: (a) What are the differences in the skin and gut microbiomes of amphibians living at high versus low altitudes? (b) Which functions are associated with the skin and gut microbiomes of frogs living at different altitudes? (c) What are the potential relationships between the frog symbiotic microbiome and the environmental microbial community?
Both altitude and host species may exert significant selective pressure on the composition of skin and gut microbes detected in Bufo gargarizans (Bg) and other amphibians

Summary

| INTRODUCTION

Symbiotic microbes play important roles in host disease immunity (Hooper, Dan, & Macpherson, 2012) and environmental adaptation (Lavrinienko, Tukalenko, Mappes, & Watts, 2018). The results of previous studies showed that plateau pika have a lower dietary diversity (types of food) than Daurian pika, the amount of gut microbes (Prevotella and Ruminococcus) was higher in plateau pika, which could improve their ability to digest plants and increase the observed levels of biodegradation (Li et al, 2018) Taken together, these studies show that an increased abundance of specific gut microorganisms improves the overall digestibility of nutrients in mammals living at high altitude (Li et al, 2018; Zhang et al, 2016; Zhao et al, 2018). Compared with the skin microbe composition of other animals living on plateaus, the composition of amphibian skin microbes may be especially important in helping them adapt to the high-altitude environment (Zeng et al, 2017). On the basis of the microbial data derived from high-throughput sequencing of the bacterial 16S rRNA gene in the gut and skin samples, we asked the following three questions: (a) What are the differences in the skin and gut microbiomes of amphibians living at high versus low altitudes? (b) Which functions are associated with the skin and gut microbiomes of frogs living at different altitudes? (c) What are the potential relationships between the frog symbiotic microbiome and the environmental microbial community (e.g., aquatic microbial community)?

| MATERIALS AND METHODS

Findings

| DISCUSSION

| CONCLUSIONS