Table_2_Variations in gut microbiota associated with changes in life-history traits of Daphnia galeata induced by fish kairomones.xlsx

The gut microbiota plays a crucial role in host physiology and the disruption of host–microbiota relationships caused by environmental stressors can impact host growth and survival. In this study, we used Daphnia galeata as a model organism to investigate the interactive effects of fish kairomones on the life-history traits and gut microbiota alterations of D. galeata, as well as the relationship between life-history traits and gut microbiota composition. The presence of fish kairomones enhanced fecundity, decreased growth, and altered gut microbiota, with significant changes in alpha diversity but not in beta diversity in the genotype KB5 of D. galeata. Statistical analysis revealed that the relative abundance of the Pseudomonadaceae family significantly increased upon exposure to fish kairomone, while the relative abundance of the Comamonadaceae family significantly decreased. The decreased growth in genotype KB5 may be associated with a significant increase in Pseudomonas, a member of the family Pseudomonadaceae, which is generally deficient in essential fatty acids, potentially negatively impacting growth. Meanwhile, it is speculated that the significant decrease in Limnohabitans belonging to the Comamonadaceae family is associated with the reduction of body size and increased fecundity of KB5 when exposed to fish kairomones. Furthermore, the genus Candidatus Protochlamydia was observed only under the fish kairomones-treated condition. These data suggest that variations in host life-history traits related to reproduction and growth are potentially associated with the relative abundance or presence of these microbial genera. Our research findings provide valuable insights into understanding the impact of biotic stress on the interaction between hosts and microbiota.

肠道微生物群（gut microbiota）在宿主生理过程中发挥关键作用，环境胁迫因子引发的宿主-微生物群关系紊乱，可对宿主的生长与存活造成负面影响。本研究以盔形溞（Daphnia galeata）作为模式生物，探究鱼类利它素（fish kairomones）对盔形溞生活史特征与肠道微生物群变化的交互影响，以及生活史特征与肠道微生物群组成之间的关联。在盔形溞KB5基因型中，鱼类利它素的存在提升了宿主繁殖力、抑制了生长，并改变了肠道微生物群结构：其α多样性发生显著变化，而β多样性无明显改变。统计学分析显示，暴露于鱼类利它素环境后，假单胞菌科（Pseudomonadaceae）的相对丰度显著升高，而丛毛单胞菌科（Comamonadaceae）的相对丰度显著降低。KB5基因型的生长抑制现象，可能与假单胞菌属（Pseudomonas，假单胞菌科成员）的丰度显著升高相关——该属细菌普遍缺乏必需脂肪酸（essential fatty acids），可能对宿主生长产生负面影响。与此同时，我们推测隶属于丛毛单胞菌科的湖栖杆菌属（Limnohabitans）丰度显著下降，与KB5在鱼类利它素暴露下的体型缩小及繁殖力提升存在关联。此外，候选原衣原体属（Candidatus Protochlamydia）仅在鱼类利它素处理组中被检测到。上述数据表明，宿主与繁殖和生长相关的生活史特征变化，可能与这些微生物属的相对丰度或存在与否存在关联。本研究结果为理解生物胁迫对宿主与微生物群互作的影响提供了重要见解。