Table_1_Microbial communities are thermally more sensitive in warm-climate lizards compared with their cold-climate counterparts.DOCX

Environmental temperature affects the composition, structure, and function of the gut microbial communities in host animals. To elucidate the role of gut microbiota in thermal adaptation, we designed a 2 species × 3 temperatures experiment, whereby we acclimated adult males of two agamid lizard species (warm-climate Leiolepis reevesii and cold-climate Phrynocephalus przewalskii) to 20, 28, and 36°C for 2 weeks and then collected their fecal and small-intestinal samples to analyze and compare the microbiota using 16S rRNA gene amplicon sequencing technology. The fecal microbiota displayed more pronounced interspecific differences in microbial community than the small-intestinal microbiota in the two species occurring in thermally different regions. The response of fecal and small-intestinal microbiota to temperature increase or decrease differed between the two species, with more bacterial taxa affected by acclimation temperature in L. reevesii than in P. przewalskii. Both species, the warm-climate species in particular, could cope with temperature change by adjusting the relative abundance of functional categories associated with metabolism and environmental information processing. Functional genes associated with carbohydrate metabolism were enhanced in P. przewalskii, suggesting the contribution of the fecal microbiota to cold-climate adaptation in P. przewalskii. Taken together, our results validate the two hypotheses tested, of which one suggests that the gut microbiota should help lizards adapt to thermal environments in which they live, and the other suggests that microbial communities should be thermally more sensitive in warm-climate lizards than in cold-climate lizards.

环境温度对宿主动物肠道微生物群落的组成、结构和功能产生显著影响。为了阐明肠道微生物群在热适应性中所扮演的角色，本研究设计了一项包含两种物种和三种温度的实验。具体而言，我们将两种壁虎科蜥蜴物种（暖气候的豹斑壁虎Leiolepis reevesii和冷气候的普氏原蜥蜴Phrynocephalus przewalskii）的成年雄性动物适应于20°C、28°C和36°C的温度条件，持续两周，随后收集它们的粪便和回肠样本，利用16S rRNA基因扩增子测序技术进行分析和比较微生物群落。在两种在温度不同的区域分布的物种中，粪便微生物群在微生物群落间的种间差异比回肠微生物群更为显著。粪便和回肠微生物群对温度上升或下降的反应在两种物种之间存在差异，L. reevesii受适应温度影响的细菌类群多于P. przewalskii。两种物种，尤其是暖气候物种，能够通过调整与代谢和环境信息处理相关的功能类群的相对丰度来应对温度变化。与碳水化合物代谢相关的功能基因在P. przewalskii中得到增强，这表明粪便微生物群对P. przewalskii的冷气候适应性有所贡献。综上所述，我们的研究验证了所测试的两个假设，其一为肠道微生物群应有助于蜥蜴适应其所处的热环境，其二为微生物群落对暖气候蜥蜴的热敏感性应高于冷气候蜥蜴。