Abstract

Females of 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' reproductive success, for instance, if they received non-nutritive gifts (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. The worthless gift tactic is expected to be less successful as females should prefer to mate and to mate for longer with males offering nutritive gifts. However, at the moment, the scarce information suggests that both mating tactics may have similar reproductive 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). We found that the females accepted to mate with courting males independently of gift type, mating order, or size. But, mating duration was positively correlated with male size, and longer when males offered worthless gifts. Furthermore, females' fecundity increased with mating duration and female size. This demonstrated that males offering worthless gifts might enhance their reproductive success by transferring more sperm than those offering nutritive gifts. Thus, either due to female choice or male effort, male size might be a more relevant feature for reproductive success than gift type, which can explain the high frequencies of worthless gifts in the field.