POLYANDRY AND ENHANCED REPRODUCTIVE SUCCESS IN THE HARLEQUIN-BEETLE-RIDING PSEUDOSCORPION

The growing molecular evidence that females of many species mate with several males calls for a critical reassessment of the selective force s which act to shape female mating tactics. In natural populations of the harlequin-beetle-riding pseudoscorpion, Cordylochernes scorpioides , females are polyandrous and typically produce mixed-paternity broods . Laboratory behavioral analyses and breeding experiments indicate tha t polyandry in this pseudoscorpion is an active strategy which increas es female reproductive success. Females restricted to mating with a si ngle male experienced a higher rate of embryo failure and produced sig nificantly fewer offspring than either females mated to more than one male in the laboratory or females naturally inseminated in the field. Forced copulation, insufficient sperm from a single mating, male nutri ent donations and variation in inherent male genetic quality cannot ex plain the greater number of nymphs hatched by polyandrous females in t his study. Evidence suggests that, by mating with several males, C. sc orpioicles females may exploit postcopulatory mechanisms for reducing the risk and/or cost of embryo failure resulting from fertilization by genetically incompatible sperm.