Table 3.

Gene ontogeny (GO) categories significantly enriched in genes experiencing positive selection

Category	Description	No. of genes			Fold enrichmentc	P-valued
		Tested	PSGa	E[PSG]b
Molecular Function
GO:0004252	Serine-type endopeptidase activity	36	15	5.6	2.7	0.0003
GO:0004930	G-protein coupled receptor activity	45	15	7.0	2.2	0.0020
GO:0005328	Neurotransmitter sodium symporter activity	17	9	2.6	3.4	0.0001
GO:0005509	Calcium ion binding	140	42	21.6	1.9	<0.0001
GO:0008484	Sulfuric ester hydrolase activity	23	10	3.6	2.8	0.0013
Cellular Component
GO:0016020	Membrane	546	120	84.4	1.4	0.0001
Biological Process
GO:0006508	Proteolysis	147	36	22.7	1.6	0.0027
GO:0006836	Neurotransmitter transport	17	9	2.6	3.4	0.0002
GO:0007156	Homophilic cell adhesion	14	8	2.2	3.7	0.0003

^aPositively Selected Gene

^bExpected number of PSGs

^cFold enrichment of observed PSGs to E[PSGs]

^dEmpirical P-values were determined by the hypergeometric with 10,000 re-samplings from a total of 6520 genes tested and 1008 identified as PSGs. All remain significant at a False Discovery Rate of 10%