Table 1.

BACLs for which a representative MAG was included in the population genomic analysis and their overall SNV frequency (number of variant loci/genome size) and mean within-sample nucleotide diversity (π). The table is ordered by taxonomy.

Baltic Cluster	Genome size (bp)	Number variant loci	SNP frequency	Mean intra-sample π	Phylum	Family	Genus
BACL13	1404359	2954	0.0021	0.0006	Crenarchaeota	Nitrosopumilaceae	Nitrosopumilus
BACL27	1786241	26173	0.0147	0.0033	Actinobacteriota	Ilumatobacteraceae	BACL27
BACL17	1756084	22436	0.0128	0.0026	Actinobacteriota	Ilumatobacteraceae	UBA3006
BACL6	2791422	12221	0.0044	0.0011	Actinobacteriota	Ilumatobacteraceae	UBA3006
BACL112	1305743	13388	0.0103	0.0029	Actinobacteriota	AcAMD-5	ATZT02
BACL2	1227951	23983	0.0195	0.004	Actinobacteriota	Nanopelagicaceae	MAG-120802
BACL15	1276454	8011	0.0063	0.0015	Actinobacteriota	Nanopelagicaceae	Planktophila
BACL18	1767133	14674	0.0083	0.0016	Bacteroidota	Cryomorphaceae	TMED14
BACL8	2159345	6697	0.0031	0.0008	Bacteroidota	Flavobacteriaceae	MAG-120531
BACL327	1850878	26602	0.0144	0.0034	Cyanobacteria	Cyanobiaceae	PCC7001
BACL325	838244	15671	0.0187	0.0038	Proteobacteria	Pelagibacteraceae	NA
BACL144	1246612	17204	0.0138	0.003	Proteobacteria	Pelagibacteraceae	NA
BACL149	1310694	13757	0.0105	0.0026	Proteobacteria	Pelagibacteraceae	IMCC9063
BACL53	1312850	23119	0.0176	0.0032	Proteobacteria	Pelagibacteraceae	IMCC9063
BACL5	1242356	8386	0.0068	0.0016	Proteobacteria	Pelagibacteraceae	Pelagibacter
BACL262	1130444	12534	0.0111	0.0026	Proteobacteria	Pelagibacteraceae	Pelagibacter
BACL214	2228508	25432	0.0114	0.0024	Proteobacteria	Burkholderiaceae	UBA2463
BACL14	1388129	7055	0.0051	0.0013	Proteobacteria	Methylophilaceae	BACL14
BACL3	2958067	16697	0.0056	0.0013	Proteobacteria	Pseudohongiellaceae	OM182
BACL1	1513717	15731	0.0104	0.0018	Proteobacteria	D2472	D2472
BACL168	2226010	4876	0.0022	0.0005	Verrucomicrobiota	NA	NA
BACL9	1774586	12495	0.007	0.0018	Verrucomicrobiota	UBA3015	UBA3015