Table S3: Signature gene sequences from phages and primary isolates collected from the four cruises reported in this study (A) DNA polymerase gene sequences from T7-like phages # Primary isolate ID 9ecp Accession number KM113820 Host 5e 7g d67f2 c7e4 Syn CC9605 Date isolated March 2010 Site of isolation Red Sea, IUI pier, 0m Details of phages and primary isolates with nearidentical sequences 11 phages or primary isolates Above 99% identity to S-TIP67 Isolated on Syn CC9605 and Pro MED4 From March 2009, August 2009 and 2010 cruises KM113811 Pro MED4 March 2009 Red Sea, IUI pier, 0m KM113818 Pro MED4 March 2009 Red Sea, IUI pier, 0m Pro MED4 August 2010 Red Sea, St. A, 20m Syn CC9605 August 2010 Red Sea, IUI pier, 0m Pro MED4 August 2010 Red Sea, St. A, 60m 4 phages or primary isolates Above 99% identity to P-TIP42 Isolated on Pro MED4 From March 2009 cruise 7 phages or primary isolates Above 97% identity to P-TIP44 Isolated on Pro MED4, MIT9215 and NATL2A From March 2009, August 2009 and 2010 cruises 3 phages or primary isolates Above 99% identity to P-TIP43 Isolated on Pro MED4 and MIT9215 From March 2009 and August 2010 cruises 3 primary isolates Above 99% identity to dp8b1 Isolated on Syn CC9605 and Pro MED4 From August 2010 2 primary isolates Above 99% identity to 7fdp3 Isolated on Pro MED4 From March 2009 cruise Less than 97% identity to other sequences KM113824 KM113823 6ed6p KM113816 4f KM113810 Near identical sequences to representative: Phage ID – GenBank accession number &# S-TIP67 – KC507138 &# 10G – KC507119 # 4dc – KM113809 2fc6 – KM113808; 7dc6 – KM113817 6bc6 – KM113814; 9ec6 – KM113819 11ec6 – KM113822; 5gcp – KM113813 11bc6 – KM113821 &# P-TIP42 – KC507139 6b – KM113815 5f – KM113812 P-TIP44 – KC507140 9f – KC507123 &# 5en – KC507121 & & P-TIP43 – KC507141 5d – KC507122 & & c8b4 – KC507105 dp8b1 – KC507106 & &# 7fdp3 – KC507110 & Pro August Red Sea, MIT9215 2010 St. A, 20m # Phage sequences used for treeing in Suppl. Fig. 1. & Phages and primary isolates collected during the four cruises reported here and presented previously in Dekel-Bird et al. (2013); The S-TIP41 phage and 4dn primary isolate were isolated from these cruises and appear in Dekel-Bird et al. (2013) but are not shown in this table. Three additional sequences were of low quality and were not included in this analysis. Syn = Synechococcus, Pro = Prochlorococcus B) Portal protein gene (g20) sequences from T4-like phages # Primary isolate name 2Bnp 8G092 5Bnp 6Bnp 2Gdp 2B096 4B092 8B092 8B026 7Gmp Accession number KM113830 KM113842 KM113835 KM113836 KM113831 KM113829 KM113833 KM113841 KM113840 KM113839 Host Date isolated Site of isolation Pro NATL2A Syn WH8109 Pro NATL2A Pro NATL2A Pro MED4 Syn WH8109 Syn WH8109 Syn WH8109 Syn WH8102 Pro MIT9215 March 2009 March 2009 August 09 March 2010 March 2010 March 2010 March 2010 March 2010 March 2010 August 2010 Red Sea, IUI pier, 0m Red Sea, St. A, 20m Red Sea, IUI pier, 0m Red Sea, IUI pier, 0m Red Sea, IUI pier, 0m Red Sea, St. A, 60m Red Sea, St. A, 20m Red Sea, St. A, 20m Red Sea, St. A, 60m Red Sea, IUI pier, 0m Details of phages and primary isolates with nearidentical sequences Less than 97% identity to other sequences Less than 97% identity to other sequences Less than 97% identity to other sequences Above 97% identity to P-SSM5 Less than 97% identity to other sequences Less than 97% identity to other sequences Less than 97% identity to other sequences Less than 97% identity to other sequences Less than 97% identity to other sequences 2 primary isolates with above 99% identity Isolated on Pro MIT9215 From March 2009 cruise Less than 97% identity to other sequences Less than 97% identity to other sequences Less than 97% identity to other sequences Above 97% identity to P-SSM5 5Bd2 KM113834 Pro MED4 August 2010 Red Sea, St. A, 20m 7E02p KM113837 Syn WH8102 August 2010 Red Sea, IUI pier, 0m 7G09p KM113838 Syn WH8109 August 2010 Red Sea, IUI pier, 0m 4B09p KM113832 Syn WH8109 August 2010 Red Sea, IUI pier, 0m # Phage sequences used for treeing in Suppl. Fig. 2. One additional sequence was of low quality and was not included in this analysis; Syn = Synechococcus, Pro = Prochlorococcus (C) DNA polymerase gene sequences from TIM5-like phages # Phage/primary isolate name S-TIM5 Accession number JQ245707 Host S-TIM54 KM113825 Syn WH8102 6C KM113826 Syn CC9605 9E KM113827 Syn WH8102 7B KM113828 Syn WH8102 # Syn WH8102 Date isolated October 2008 Site of isolation Details of primary isolates with identical DNA polymerase gene sequences Red Sea, IUI pier, 0m 10 primary isolates Identical to the archetype phage Isolated on Syn WH8102 and CC9605 hosts From all 4 cruises March 2009 March 2010 Red Sea St. A, 20m Red Sea, IUI pier, 0m March 2010 August 2010 Red Sea St. A, 20m Red Sea, IUI pier, 0m Phage sequences used for treeing in Suppl. Fig. 3. Syn = Synechococcus 3 primary isolates Isolated on Syn CC9605 From Aug 2009 and March 2010 cruises 52 primary isolates Isolated on Syn WH8102 and CC9605 hosts From all 4 cruises