Unraveling the predictive role of temperature in the gut microbiota of the sea urchin Echinometra sp. EZ across spatial and temporal gradients

Shifts in microbial communities represent a rapid response mechanism for host organisms to respond to changes in environmental conditions. Therefore, they are likely to be important in assisting the acclimatization of hosts to seasonal temperature changes as well as to variation in temperatures across a species’ range. The Persian/Arabian Gulf is the world's warmest sea, with large seasonal fluctuations in temperature (20℃ - 37℃) and is connected to the Gulf of Oman which experiences more typical oceanic conditions (<32℃ in the summer). This system is an informative model for understanding how symbiotic microbial assemblages respond to thermal variation across temporal and spatial scales. Here, we elucidate the role of temperature on the microbial gut community of the sea urchin Echinometra sp. EZ and identify microbial taxa that are tightly correlated with the thermal environment. We generated two independent datasets with a high degree of geographic and temporal resolution. The results show that microbial communities vary across thermally variable habitats, display temporal shifts that correlate with temperature, and can become more disperse as temperatures rise. The relative abundances of several ASVs significantly correlate with temperature in both independent datasets despite the >300 km distance between the furthest sites and the extreme seasonal variations. Notably, over 50% of the temperature predictive ASVs identified from the two datasets belonged to the family Vibrionaceae. Together, our results identify temperature as a robust predictor of community-level variation and highlight specific microbial taxa putatively involved in the response to thermal environment.

Methods
Please see manuscript.

微生物群落的动态变化是宿主响应环境条件改变的快速应答机制，因此其在协助宿主适应季节性温度波动，以及跨物种分布范围的温度变化中具有重要作用。
波斯湾/阿拉伯海湾是全球水温最高的海域，其温度存在显著的季节性波动（20℃-37℃），且与夏季水温维持典型海洋环境水平（低于32℃）的阿曼湾相连。该生态系统是探究共生微生物群落如何在时间与空间尺度上响应温度变化的理想研究模型。
本研究阐明了温度对海胆Echinometra sp. EZ肠道微生物群落的调控作用，并筛选出与温度环境紧密相关的微生物类群。我们构建了两套具备高地理与时间分辨率的独立数据集。
研究结果显示，微生物群落在热环境异质的生境中存在显著分化，呈现出与温度相关的时间动态变化，且随温度升高群落分布愈发离散。尽管最远采样点间距超过300公里且存在极端季节性温度波动，若干扩增子序列变体（Amplicon Sequence Variants，ASVs）的相对丰度在两套独立数据集中均与温度显著相关。值得注意的是，从两套数据集中筛选出的温度响应型ASVs中，超过50%隶属于弧菌科（Vibrionaceae）。综上，本研究证实温度是驱动群落水平微生物变异的可靠预测因子，并明确了若干可能参与宿主热环境应答的特异性微生物类群。

研究方法
详见研究手稿。