Sperm depletion and mate choice of the crab spider, Ebrechtella tricuspidata (Fahricius).

Abstract

Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings, resulting in the decline of female reproductive output in insect species. It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males, such as mating multiply with different males and/or discriminating against previously mated males (MMs). Similarly, males may exhibit adaptive behaviors toward females varying in mating status. However, in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm, there are few studies on male mating potential and previous mating experience on their subsequent mate choice. In this study, we used a polyandrous crab spider, Ebrechtella tricuspidata, a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1) male mating experiences influence female reproductive fitness; 2) females respond differently to males varying in mating status; and 3) males respond differently to females varying in mating status. Our results showed that female fecundity was independent of male mating experiences, but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac. Counter to our predictions, females preferred to choose and mate with the larger males, regardless of their mating status. In contrast, male mating status influenced their mating preference toward females. Virgin males did not show any preference between virgin and mated females; however, MMs were more likely to prefer the virgin females over the mated ones. Overall, our results indicated that female choice depended primarily on male relative size rather than male mating status, whereas male choice depended on female mating status. Depending on the investigation of reproductive dynamics and mate choice in E. tricuspidata, the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying in mating status.