The Combined Effect of Temperature and Host Clonal Line on the Microbiota of a Planktonic Crustacean.

Host-associated microbiota vary across host individuals and environmental conditions, but the relative importance of their genetic background versus their environment is difficult to disentangle. We sought to experimentally determine the factors shaping the microbiota of the planktonic Crustacean, Daphnia magna. We used clonal lines from a wide geographic distribution, which had been kept under standardized conditions for over 75 generations. Replicate populations were kept for three generations at 20 and 28 °C. The interaction of the host clonal line and environment (i.e., temperature) influenced microbiota community characteristics, including structure, the relative abundance of common microbial species, and the microbial richness and phylogenetic diversity. We did not find any correlation between host-associated microbiota and the geographic origin of the clones or their temperature tolerance. Our results highlight the prominent effects that host clonal lineage and its interaction with the environment has on host-associated microbiota composition.