Pandulli-Alonso et al Ethology
Description
Females from nuptial gift-giving species are known to mate with several males so that they secure multiple ejaculates and food via nuptial gifts. However, gifts may decrease females fitness success, for instance, if the male offer a non-nutritive gift (worthless). The gift-giving mating system of the spider Paratrechalea ornata creates a scenario in which females may receive either a nutritive prey or a worthless inedible item wrapped in silk. Because receiving a worthless gift reduces the food consumed by females, this tactic is expected to be less successful. However, at the moment, the scarce information suggests that both mating tactics may have similar fitness success. By exposing females to a double mating experimental design, we examined whether mating access and duration correlate with the gift type (nutritive-worthless), mating order (first-second) and male size; and additionally explored possible effects on female fitness (e.g. fecundity). In the N-W group (n = 18), the female mated first with a male offering a nutritive gift (N) consisting in a housefly (Musca domestica) and second with a male offering a worthless gift (W) consisting in an exuviae of Tenebrio molitor larva. In the W-N group (n = 21), the female mated first with a male offering a worthless gift and second with a male offering a nutritive one. We found that the females accepted to mate with courting males independently of gift type, mating order or size. But, mating duration positively correlated with male size, an effect boosted when offering worthless gifts. Further, females’ fecundity increased with mating duration and female size. This demonstrated that when they are large, males offering worthless gifts might enhance their reproductive success by transferring more sperm than those offering nutritive gifts. It is known that worthless gifts can occur in high frequencies in the field (45-96%), thus, either due to females choice or males effort, male size might be a more relevant feature for reproductive success than gift type.