Heritability of sperm competition success in the bulb mite,Rhizoglyphus robini

Multiple mating by females has been proposed to function as a form of mate-choice, which implies that males should show heritable variation in sperm-competitive abilities. In this study, repeatability and heritability of sperm competition success was estimated in the bulb mite, Rhizoglyphus robini. Fertilization success of males was estimated in competition with sperm of two other males. Males differed consistently in their sperm competition success, with repeatability estimated at 0.22. The heritability of sperm competition success was estimated using parent-offspring regression, with the mean fertilization success from two matings used as a measure of each male's competitive ability. There was a significant association between the sperm competition success of fathers and sons. Narrow sense heritability (h²) was 0.284. This result supports the hypotheses proposing the multiple mating is selectively maintained in females by enhancing the reproductive success of their progeny.