Table 2. Codons under negative selection identified by both SLAC and FEL analyses.

Numbers for codon position correspond to amino acid numbers for An. gambiae as indicated in the alignment in Figure 1. Codon positions and amino acids predicted to be involved in protein binding are in bold.

Codon Position	Amino Acidsa	Categoryb	ω SLAC	P-value	ω FEL	P-value
38	E15	charged	0	0.006603	0	0.000768
42	D15	charged	0	0.001918	0	0.000102
50	N12, H3	polar	0.063	0.000755	0.034	0.000160
53	L14, H1	hydrophobic	0.099	0.009734	0.080	0.004253
58	L15	hydrophobic	0	0.002737	0	0.000036
73	R15	charged	0	0.008455	0	0.000972
81	G15	hydrophobic	0	0.000476	0	0.000027
83	H11, R3, L1	polar	0.112	0.003022	0.012	0.000027
90	V14, I1	hydrophobic	0.070	0.002433	0.014	0.000043
91	G15	hydrophobic	0	0.004328	0	0.000302
101	T15	polar	0	0.004328	0	0.000085
104	D11, N4	charged	0.037	0.001294	0.026	0.000764
112	P15	hydrophobic	0	0.004115	0	0.000082
113	T15	polar	0	0.004115	0	0.000049
125	V15	hydrophobic	0	0.004115	0	0.001721
129	Q15	polar	0	0.000303	0	0.000011
140	S15	polar	0	0.004818	0	0.000034
141	G15	hydrophobic	0	0.004186	0	0.000197
144	G15	hydrophobic	0	0.004276	0	0.000544
148	I11, V4	hydrophobic	0.060	0.003162	0.038	0.000294
151	V14, M1	hydrophobic	0.082	0.006518	0.048	0.001644
153	E15	charged	0	0.006568	0	0.001085
164	A15	hydrophobic	0	0.000457	0	0.000021
166	I15	polar	0	0.000119	0	0.000001
168	G15	hydrophobic	0	0.004611	0	0.000405

^aFor each codon position, all amino acids present in the alignment are provided with the frequency indicated by the subscript.

^bAmino acids were categorized into three broad groups based on physicochemical properties of side chains (Wolfenden et al., 1981): hydrophobic - A, F, G, I, L, P, V, W; polar - C, H, M, N, Q, S, T, Y; charged - D, E, K, R.