Table 3. Rapidly evolving sperm genes involved in different reproductive processes.

Reproductive process	Number of geneswith dN/dS >0.5	Proportion of geneswith dN/dS >0.5	Expected proportion ofgenes with dN/dS >0.5	Observed- expected
Spermatogenesis	6	24.0	20.0	4.0
Sperm metabolism	3	8.0	13.94	−5.94
Sperm motility	4	20.0	20.61	−0.61
Capacitation	1	4.0	12.73	−8.73
Acrosome reaction	2	8.0	12.12	−4.12
Sperm-egg interaction	9	36.0	20.61	15.39

The proportion of sperm genes with ω >0.5 is shown for each group. Expected proportions were calculated as the percentage of genes of each group in the total sample. Differences between observed and expected proportions are presented.