Transmission of microbiota between host linages in Daphnia pulex

Although host-associated microbiota is thought to be influenced by host genetic and environmental factors, the relative importance of host genetic factors on the microbiota is not always evident. In this study, we evaluated the influence of genetic factors on the microbiota of Daphnia pulex in Japan by comparing the host-associated microbiota with and without a mixture of different lineage daphnids. Of the D. pulex genotypes inhabiting Japan, the A1 and A5 genotypes were used from the JPN1 lineage, which is widely distributed, and the C and G genotypes from the JPN2 lineage, mainly distributed in eastern Japan and northward. From these genotypes, mixed rearing bottles were established in which two individuals each from different lineages were reared in the same container under constant food and temperature conditions, and single rearing bottles in which four individuals of the same genotype were reared in the same bottles under the same conditions. After seven days of rearing, each individual was collected, DNA was extracted, and the genotypes of the individuals in the mixed rearing bottles were determined using the PCR-RFLP method. The extracted DNA was subjected to PCR with universal primers in the V3-V4 region of the bacterial 16s rRNA gene and amplicon sequencing using MiSeq to obtain genomic data.