Table 1. Results of least squares fitting between vector distance of genome pairs and their GC content difference.

	Slope	Intercept	SSE	R-square
Base distance	1.968	0.05285	4332	0.9732
Codon distance	2.532	0.2871	2.556e+004	0.9108
Amino acid distance	1.185	0.09203	1.356e+004	0.8069