Strain-level phylogenetic trees for microbes present in both the mother and infant. Strain-level phylogenetic trees for microbes present in both the mother and infant. Phylogenetic trees were built by the StrainPhlAn method using species-specific markers confirming the presence of the same strain in the mother and infant intestinal microbiomes, thus suggesting vertical transmission. Available reference genomes were included in the phylogenetic trees. Here we report three bacterial species, namely, (A) Bifidobacterium bifidum, (B) Coprococcus comes, and (C) Ruminococcus bromii, and the most abundant viral species found in pair 4, (D) pepper mild mottle virus. Other species-specific phylogenetic trees (B. adolescentis, B. breve, and B. longum) are reported in Fig. S3. Francesco Asnicar et al. mSystems 2017; doi:10.1128/mSystems.00164-16