Table 2.

Mutation and evolutionary rates of the genome and S1 genes for California (CAL), Connecticut (Conn) and Massachusetts (Mass) isolates.

Virus type	Mutation rate (nucleotide changes/year)		Evolutionary rate (amino acid changes/year)
	Genomea	S1 geneb	Genomea	S1 geneb
CAL	1.0 × 10−2	9.4 × 10−4	2.0 × 10−2	2.4 × 10−3
Conn	1.5 × 10−4	1.7 × 10−4	2.6 × 10−4	3.5 × 10−4
Mass	1.9 × 10−3	2.4 × 10−4	3.3 × 10−3	5.8 × 10−4

^aViruses used in the genome analysis were the CAL, Conn and Mass viruses shown in Fig. 1.

^bViruses used in the S1 gene analysis are the same viruses shown in Table 1.