Table 2. Numbers of functional and nonfunctional OR genes belonging to different groups in six species.

	Zebrafish		Pufferfish		X. tropicalis		Chicken		Mouse†		Human†
Group*	Funct	Total	Funct	Total	Funct	Total	Funct	Total	Funct	Total	Funct	Total
α (I)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	2 (0.5)	6 (0.7)	9 (11.0)	14 (2.5)	115 (11.1)	163 (11.7)	57 (14.7)	102 (12.7)
β (I)	1 (1.0)	2 (1.5)	1 (2.3)	1 (1.0)	5 (1.2)	19 (2.1)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
γ (II)	1 (1.0)	1 (0.7)	0 (0.0)	0 (0.0)	370 (90.2)	802 (90.3)	72 (87.8)	543 (97.3)	922 (88.9)	1,228 (88.3)	331 (85.3)	700 (87.3)
δ (I)	44 (43.1)	55 (40.1)	28 (63.6)	61 (62.2)	22 (5.4)	36 (4.1)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
ε (I)	11 (10.8)	14 (10.2)	2 (4.5)	2 (2.0)	6 (1.5)	17 (1.9)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
ζ (I)	27 (26.5)	40 (29.2)	6 (13.6)	8 (8.2)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
η	16 (15.7)	23 (16.8)	5 (11.4)	24 (24.5)	3 (0.7)	6 (0.7)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
Θ	1 (1.0)	1 (0.7)	1 (2.3)	1 (1.0)	1 (0.2)	1 (0.1)	1 (1.2)	1 (0.2)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
κ	1 (1.0)	1 (0.7)	1 (2.3)	1 (1.0)	1 (0.2)	1 (0.1)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
Total	102 (100.0)	137 (100.0)	44 (100.0)	98 (100.0)	410 (100.0)	888 (100.0)	82 (100.0)	558 (100.0)	1,037 (100.0)	1,391 (100.0)	388 (100.0)	802 (100.0)

The numbers in parentheses represent the percentage of genes for each group. Funct, functional genes; Total, total number of genes including functional genes, pseudogenes, and partial sequences.

^*(I) and (II) indicate class I and II, respectively, in the currently accepted classification of vertebrate OR genes. Groups η, Θ, and κ were newly identified in this study and therefore are neither class I nor class II.

^†The data for humans and mice were obtained from refs. 5 and 9, respectively.