Anti-predation Defense Traits of Daphnia are Associated With the Gut Microbiota Composition Shaped by Fish Kairomone

Abstract

Background: Gut microbiota plays an important role in host physiology and fitness. The gut microbiota can promote host health by influencing life history traits, especially in arthropods. However, it is not clear whether the performance of host defense traits in response to predator pressure in natural food webs is related to their gut microbiota composition. In this study, we used Daphnia magna as a model organism to investigate the relationship of D. magna life history traits and gut microbiota alterations under predator kairomone based on 16S rRNA amplicon sequencing.Result: We showed that the microbiota composition of D. magna was significantly affected by their predator risk and development stage. The relative abundance of Comamonadaceae (mainly Limnohabitans sp.) significantly decreased in the presence of predator kairomone. Furthermore, the presence of predator kairomone significantly reduced the α diversity of gut microbiota in D. magna with the increase of instar. Among them, the OTUs belonged to Epsilonbacteraeota and Firmicutes in the presence of predator kairomone were significantly higher than those in the control group. The results of functional predictions showed that predation pressure promote the metabolic function of gut microbiota, such as metabolism of energy, cofactors, and vitamins. By analyzing the correlation between the induced defense traits of D. magna and the relative abundance of bacteria, we found that the increased abundance of Comamonadaceae, Moraxellaceae, and Flavobacteriaceae were linearly correlated with the partial defense traits of D. magna. Specifically speaking, body size was positively correlated with an increased abundance of Comamonadaceae, whereas spine length was negatively correlated with an increased abundance of Comamonadaceae but was positively correlated with increased Flavobacteriaceae abundance. Conclusions: Our results suggested that predation risk can affect the composition of the gut microbiota in D. magna, which may indirectly induce the production of defensive traits in D. magna. The results of this study revealed an important role of gut microbiota in the development of defensive traits of Daphnia in response to fish predators. The correlation between microbial abundance and defense traits is of great significance for further understanding the effect of host-microbiota interaction on individual anti-predation defense.

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

“…predict the gut microbiome's impact on the by understanding the microbiome community and investigating associations between variations in the gut microbiome and host phenotypes (Liu et al, 2021). Similar to numerous eukaryotes, Daphnia hosts a diverse community of microbes externally and internally (Qi et al, 2009).…”

“…In addition, previous studies have shown that environmental factors, such as biotic and abiotic stress, can influence the gut microbial community of Daphnia (Akbar et al, 2022). For example, a recent study showed that predation pressure can induce antipredation defense traits in Daphnia magna and reconfigure the composition of the gut microbiota, highlighting a complex correlation between induced defense traits and altered gut microbiota (Liu et al, 2021). In this study, we examined changes in life-history traits induced by fish kairomones, the diversity and composition of the gut microbiota and the differential abundance of bacteria.…”