Table_2_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.

环境温度会影响宿主动物肠道微生物群落的组成、结构与功能。为阐明肠道菌群在温度适应中的作用，我们设计了一项2物种×3温度梯度的实验：将两种鬣蜥科蜥蜴的成年雄性个体——暖气候型的蜡皮蜥（Leiolepis reevesii）与冷气候型的草原沙蜥（Phrynocephalus przewalskii），分别置于20℃、28℃、36℃环境中驯化2周，随后收集其粪便与小肠样本，采用16S rRNA基因扩增子测序技术对肠道菌群进行分析与比较。对于栖息于不同温度环境的这两种蜥蜴而言，粪便菌群的群落种间差异相较于小肠菌群更为显著。两种蜥蜴的粪便与小肠菌群对温度升降的响应模式存在差异，其中蜡皮蜥（L. reevesii）受驯化温度影响的细菌类群数量多于草原沙蜥（P. przewalskii）。两种蜥蜴均可通过调控与代谢及环境信息加工相关的功能类群的相对丰度来应对温度变化，其中暖气候型物种的响应尤为突出。草原沙蜥（P. przewalskii）体内与碳水化合物代谢相关的功能基因丰度显著提升，提示粪便菌群对其冷气候适应具有积极贡献。综上，本研究结果验证了两项待检验假说：其一，肠道菌群可助力蜥蜴适应其生存的温度环境；其二，暖气候型蜥蜴的微生物群落对温度的敏感性高于冷气候型蜥蜴。