POLYANDROUS FEMALES DISCRIMINATE AGAINST PREVIOUS MATES

In most animal species, particularly those in which females engage in polyandry, mate choice is a sequential process in which a female must choose to mate or not to mate with each male encountered. Although a n umber of theoretical and empirical investigations have examined the ef fects of sequential mate choice on the operation of sexual selection, how females respond to solicitation by previous mates has received lit tle attention. Here, we report the results of a study carried out on t he polyandrous pseudoscorpion, Cordylochernes scorpioides, that assess ed the sexual receptivity of once-mated females presented after a laps e of 1.5 hr or 48 hr with either their first mate or a different male. Females exhibited a high level of receptivity to new males, irrespect ive of intermating interval. By contrast, time between matings exerted a strong effect on female receptivity to previous mates. After a laps e of 48 hr, females did not differ significantly in their receptivity toward previous mates and different males, whereas at 1.5 hr after fir st mating, females were almost invariably unreceptive to males from wh om they had previously accepted sperm. This result could not be attrib uted to male size or mating experience or to male sexual receptivity. Indeed, males were as willing to transfer sperm to a previous mate as they were to a new female. This difference between males and females i n their propensity to remate with the same individual may reflect a co nflict between the sexes, with males seeking to minimize postcopulator y sexual selection and females actively keeping open the opportunity f or sperm competition and female choice of sperm by discriminating agai nst previous mates.