The evolutionary differentiation of two histone H2A.Z variants in chordates (H2A.Z-1 and H2A.Z-2) is mediated by a stepwise mutation process that affects three amino acid residues

Table 1 Nucleotide and protein variation in the H2A variants analyzed.

	p_AA (SE)	p_NT (SE)	p_S (SE)	p_N (SE)	Z-test^a	R^b
H2A.Z-1	0.058 (0.009)	0.121 (0.008)	0.328 (0.016)	0.037 (0.006)	17.475**	1.3
H2A.Z-2	0.032 (0.006)	0.131 (0.011)	0.400 (0.020)	0.018 (0.003)	17.516**	1.4
H2A.Z-e	0.016 (0.007)	0.148 (0.013)	0.450 (0.031)	0.028 (0.009)	13.946**	1.2
Insects	0.024 (0.010)	0.203 (0.012)	0.611 (0.022)	0.037 (0.008)	24.826**	1.1
Fungi/Protists	0.309 (0.031)	0.385 (0.015)	0.710 (0.023)	0.260 (0.025)	12.886**	0.8
Overall	0.083 (0.011)	0.236 (0.019)	0.648 (0.024)	0.077 (0.009)	30.354**	0.9

Average numbers of amino acid (p_AA), nucleotide (p_NT), synonymous (p_S), and nonsynonymous (p_N) nucleotide differences per site and Z-test of selection.
Note.- SE, standard error; ** P < 0.001
^a H₀: p_N = p_S; H₁: p_N <p_S
^b Average transition/transversion ratio

ISSN: 2730-7182