Abstract
It has been well acknowledged that the gut microbiome is important for host health, composition changes in these microbial communities might increase susceptibility to infections and reduce adaptability to environment. Reintroduction, as an effective strategy for wild population recovery and genetic diversity maintenance for endangered populations, usually takes captive populations as rewilding resource. While, little is known about the compositional and functional differences of gut microbiota between captive and wild populations, especially for large carnivores, like Amur tiger. In this study, high throughput sequencing of the 16S ribosomal RNA (rRNA) gene (amplicon sequencing) and metagenomics were used to analyze the composition and function variations of gut microbiota communities between captive and wild Amur tiger populations based on total 35 fecal samples (13 from captive tigers and 22 from wild tigers). Our results showed that captive Amur tigers have higher alpha diversity in gut microbiota, but that the average unweighted UniFrac distance of bacterial taxa among wild Amur tigers was much larger. The function differences involve most aspects of the body functions, especially for metabolism, environmental information processing, cellular processes, and organismal systems. It was indicated that the diet habit and environment difference between captive and wild populations lead to composition differences of gut microbiota and then resulted in significant differences in functions. These contrasts of functional and compositional variations in gut microbiota between wild and captive Amur tigers are essential insights for guiding conservation management and policy decision-making, and call for more attention on the influence of gut microbiota on the ability of captive animals to survive in the wild.
Highlights
The gastrointestinal tracts of vertebrates are inhabited by large and diverse populations of bacteria, which play an integral role in food decomposition, nutrient supply, immune modulation, pathogen prevention, and may be an essential factor in influencing the processes of ecological adaptation (Doolittle, 1998; Round and Mazmanian, 2009; Turnbaugh et al, 2009; Gut Microbiota of Amur TigerHonda and Littman, 2012; Alberdi et al, 2016)
These reads were assigned to 1,186 unique phylotypes (OTUs) and 99.07% were successfully classified at the phylum level (n = 17), 98.73% to class (n = 35), 98.39% to order (n = 59), 97.38% to family (n = 125), and 88.61% to genus (n = 260) using the Ribosomal Database Project (RDP)
Our study provided a comprehensive catalog of the gut microbiome of Amur tigers through 16S ribosomal RNA (rRNA) gene and metagenome analysis of fecal samples
Summary
The gastrointestinal tracts of vertebrates are inhabited by large and diverse populations of bacteria, which play an integral role in food decomposition, nutrient supply, immune modulation, pathogen prevention, and may be an essential factor in influencing the processes of ecological adaptation (Doolittle, 1998; Round and Mazmanian, 2009; Turnbaugh et al, 2009; Gut Microbiota of Amur TigerHonda and Littman, 2012; Alberdi et al, 2016). Gut microbiota are indispensable for maintaining the health of hosts, because microbial imbalances may result in changes in the host’s microbial diversity and community composition, potentially leading to inflammatory bowel disease, infectious diseases, obesity, and autoimmune disorders (Frank et al, 2007; Turnbaugh et al, 2009; Moeller et al, 2014; Brune and Dietrich, 2015; Clayton et al, 2016). These host-microbial communities are potentially shaped by intrinsic host traits and extrinsic environmental factors. Characterizing the gut microbiota of mammals, living under natural conditions, is an important health issue and has significant impacts on understanding the ecological and evolutionary relationship between hosts and their gut microbiota (Nelson et al, 2013)
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