Table 2. Results of χ²-tests for nonsynonymous and synonymous substitutions in SWS1.

CF = 3 (774.4 non-synonymous sites: 239.6 synonymous sites)
	Observed		Expected
Branch(es)	N	S	N	S	ω	χ2	p value
1. Crown odontocete + crown mysticete branches	193.3	47.8	184.2	56.9	1.25	1.91	0.17
2. Odontocete stem branch	2.1	4	4.66	1.44	0.16	5.95	0.015*
3. Mysticete stem branch	6.2	2.3	6.49	2.01	0.83	0.06	0.81

χ²-tests compared the observed versus expected numbers of nonsynonymous and synonymous substitutions for SWS1 based on a neutral model of evolution (ω = 1). All three different branch categories are expected to exhibit neutral ω values according to the “coastal” hypothesis of SWS1 evolution. CF = codon frequency model; N = nonsynonymous; S = synonymous; ω = dN/dS;

^* = significant p values.