Vertical grey rectangles height is proportional to viral richness (individual genomic contig counts) at each location, aggregated across luminal and mucosal samples; thickness of coloured connectors is proportional with the number of genomic contigs of each viral family shared between pairs of locations; SI, small intestine; LI, large intestine; Prox/Mid/Dist, proximal, medial and distal portions, respectively; unclassified genomic contigs were excluded; C, fraction of viral contig diversity from each organ represented in the distal LI.