Multiple mating does not benefit females of a polyandrous pollinating fig wasp

Abstract

In some species, females vary in the numbers of times they mate. While polyandry will always be beneficial to a male that mate with a previously mated female, the effect on female fitness is unclear. From females' perspective, variation in matedness can reflect adaptive differences in females’ requirements for mating or non-adaptive chance factors. Pollinating fig wasps have been considered to be mostly monandrous although polyandry has been confirmed in a number of species. Here we first show that the pollinating fig wasp, Platyscapa awekei, is polyandrous. Second, we show that intraspecific variation in female matedness may be explained best by chance encounters between males and receptive females. The mean number of offspring does not increase with polyandry. Nor is there evidence of sperm limitation. These observations rule out direct benefits to females. Despite evidence for multiply-mated females having mated with less compatible males, multiple mating is not combined with selective preference for more compatible males' sperm, ruling out indirect benefits. Therefore variation in female matedness seems to have no fitness benefit to females and from the females' perspective may be best explained by chance variation in encounter rates between males and receptive females.