Figure 3. Tara Oceans virome similarity with associated metadata.

Average-linkage hierarchical clustering of sample UniFrac distance based on RNR sequences mined from 41 Tara Oceans viromes. Major and sub-clusters of samples (A–G) are labeled. Branch color is based on a scaled, 1-dimensional projection of sample conductivity, oxygen, and latitude onto the Viridis color gradient. Samples that are more similar to each other in branch color represent those that are more similar to each other with respect to the environmental parameters in the ordination. The first bar series (purple) represents sample conductivity (mS/cm), the second bar series (orange) represents sample dissolved oxygen levels (µmol/kg), and the third bar series (brown/green) represents sample latitude (degrees). For the first two bar series, shorter bars with lighter colors indicate lower values, while longer bars with darker colors indicate higher values. For the third series, longer, dark brown bars indicate samples with extreme negative latitudes, whereas longer, dark blue bars indicate samples with extreme positive latitudes. Samples with intermediate latitudes are represented by shorter, light colored bars. Sample labels represent the station from which the virome was acquired and are colored by sampling depth, with light blue representing surface samples and dark blue representing samples from the deep chlorophyll maximum at that station.