Figure 4

Geographic localization. (a) The different sampling sites of the Sorcerer II Global Sampling expedition. The samples 00 and 01 are part of the Sargasso Sea pilot study [16]. The inset shows samples 27 to 36, which were sampled in the Galapagos Islands. The sampling sites displayed in light gray were not analyzed in the GOS original study, nor in this study. This part of Figure 1 was reproduced from [13]. (b) Relative abundance of PolB fragments for virus groups across GOS sampling sites. The left-most panel shows the relative abundance of viral PolBs in difierent GOS samples. The mimivirus group clearly appears as the most ubiquitous after phages. Four area plots (second to fifth panels from the left) show water temperature, chlorophyll a concentration (no information was available for GS20, GS30, GS32, GS33, GS47 and GS51 sites), salinity (no information was available for GS06, GS11, GS13, GS14, GS28, GS30, GS31, GS32, GS34 and GS37 sites) and sample depth, respectively. Two far right histograms (sixth and seventh panels) show the proportion and the estimated number of reads associated with the viral PolB fragments among total reads for a given sample.