Female remating decisions and mate choice benefits in the beetle Gnatocerus cornutus

Abstract: Females usually encounter males sequentially and should discriminate between potential partners among the males that they encounter. Thus, appropriate sequential mating decisions allow females to gain mate choice benefits in the circumstance of multiple encounters. For example, if mated females can assess the genetic quality of a male prior to mating, they can remate with genetically superior males and benefit indirectly by production of offspring of superior quality (trading-up hypothesis). Additionally, because female remating generates opportunities for postcopulatory sexual selection, females can improve son quality in postcopulation processes. In the beetle Gnatocerus cornutus, females prefer mates that court vigorously before copulation and prefer attractive males, which provide indirect benefits to females because they sire attractive sons. However, there is no information about male attractiveness and the resulting fitness benefits in female remating decisions, and here we focused on this. We found that females readily remated with attractive males and that females who had mated with unattractive males readily accepted remating. Subsequently, we established four experimental treatments: a single mating with an attractive or unattractive male, mating with an attractive and then an unattractive male, and mating with an unattractive and then an attractive male. All females that mated with attractive males produced attractive sons, regardless of the order of mating with the attractive male. These results suggest that females improve son quality by trading up and biasing fertilizations toward sperm of attractive males in G. cornutus. On the other hand, no direct effect of remating on female fitness was observed. Significance statement: When females encounter males sequentially, they must choose appropriate partners among the mates that they encounter. In the beetle Gnatocerus cornutus, proper sequential mating decisions increase the likelihood of securing sperm of attractive males when females encounter multiple mates. That is, females readily remated with attractive males, and females that mated with unattractive males readily accepted remating. Additionally, they produced attractive sons regardless of the order of the mating with attractive males. This suggests that females bias fertilizations toward the sperm of attractive males to produce attractive sons. Therefore, females may produce attractive sons by remating with attractive males and biasing fertilization toward the sperm of attractive males, indirectly increasing female fitness in G. cornutus. By contrast, remating did not affect female fitness (longevity and offspring number), and so there was no direct effect of remating on female fitness.