Table 2.

Origins of the g20 sequences used in ‘meta’ phylogenetic analyses shown in Fig. 2.

# Sequences	Description	PCR-based?	Sequence label in Fig. 2	Refs
512	Environmental sequences from 42 oceanic sample sites from the GOS	N	JC#	1
56	Environmental sequences from 19 globally distributed freshwater and marine sites	Y	AY705#	2
25	Environmental sequences from Rhode Island coastal waters, USA	Y	AY259#	3
43	Environmental sequences from Lake Erie, USA	Y	DQ318#	4
47	Environmental sequences from Lake Bourget, France	Y	AY426#	5
27	Environmental sequences and mixed lysates from coastal north-western Atlantic Ocean	Y	Variable	6
51	Cultured marine cyanomyophages of variable coastal and open ocean origins	N/A	Variable	3, 7
8	Cultured non-cyanomyophages from sewage	N/A	Variable	8

The ‘PCR-based’ column indicates whether the environmental sequence was obtained by PCR or metagenomic approaches (N/A indicates that this is not applicable for sequences from cultured phage isolates). Reference code: 1, Rusch and colleagues (2007); 2, Short and Suttle (2005); 3, Marston and Salee (2003); 4, Wilhelm and colleagues (2006); 5, Dorigo and colleagues (2004); 6, Zhong and colleagues (2002); 7, this study; 8, T4-like phage genomes website http://phage.bioc.tulane.edu/