animal gut microbiome and cold adaptation

The Qinghai-Tibet Plateau is harsh environment characterized by low temperature, high altitude and hypoxia, while some native mammals on the QTP can well adapt to the extreme climate. Several reports have studied the mechanism of animals adapting to extreme environment from host physiology and genes. Intestinal microorganisms, as the second genome of animals, may also play an important role in the animal adaptation to environment. However, how animal gut microbial community structure and function adapt to extreme cold climate is not well understood. Plateau Pika (Ochotona curzoniae) is a key animal species on the Qinghai-Tibet Plateau, and has adapted to extreme plateau environment through long evolutionary processes, thus it is an ideal animal model to study the effects of climate change on host adaptation by studing intestinal microorganisms. Here, we used 16S rRNA sequencing technology combined with animal physiological and ecological methods to investigate the composition and function of gut microbiota in warm summer and cold winter. Bacteroidetes were higher in winter, while Spirochetes were more abundant in summer. Community structures also had significant separation between seasons. Due to limited diet resource, the pikas in winter had a lower ability of degradation and fermentation for plant-based food (reduced cellulase activity and total short-chain fatty acids) by decreasing gut microbial diversity and some functional microbes, such as fiber-degrading bacteria Oscillospira and Treponema. Metagenomic prediction found that most of those gene functions associated with metabolism (e.g., energy metabolism and lipid metabolism) were less abundant in winter, implying that the plateau pika slows diet fermentation and weakens energy requirements in the cold season. Our results have important significance for explaining the mechanism of wild plateau mammals adapting to high-altitude cold environment from the perspectives of gut microbiome.