Induced anti-predation defense traits of Daphnia are associated with the gut microbiota composition

Abstract A growing number of studies on gnotobiotic animals have shown that the gut microbiota can promote host health by influencing life history traits. However, it is not clear whether the performance of host defense traits is related to the gut microbiota. In this study, we used Daphnia magna as a model organism to investigate the relationship between D. magna life history anti-predation defense traits and gut microbiota alterations under fish kairomone. Results showed that the Shannon diversity of D. magna gut microbiota under fish kairomone reduced significantly with the developmental stages. By analyzing the correlation between the induced anti-predation defense traits of D. magna and the relative abundance of bacteria, we found that the abundances of Comamonadaceae , Moraxellaceae , and Flavobacteriaceae were linearly correlated with the partial anti-predation defense traits of D. magna . Furthermore, the functional categories analysis showed that fish kairomone influenced the metabolic repertoire of D. magna gut microbiota. Our results highlighted that predation risk can simultaneously induce anti-predation defense and reshape gut microbiota composition of D. magna , and there was a complex correlation between the induced defensive traits and altered-microbiota. Such results revealed an important role of gut microbiota in the development of defensive traits of Daphnia .