Sequential mate encounters: female but not male body size influences female remating behavior

Whether and how individuals choose sequentially among mates is an important but largely neglected aspect in sexual selection studies. Here, we explore female remating behavior in the cellar spider Pholcus phalangioides. We focus on body size as one of the most important traits involved in mate choice. Large and small females (n = 216) were double mated with large or small males in all eight possible combinations. All females copulated when virgin, but only 82% accepted a second male. The chance of a female remating was not significantly predicted by the body size of the second or first male or by the size difference between the two. In contrast, a previous study demonstrated a male size effect in that larger males monopolized females until egg laying when two males of different sizes were present. We suggest that sequential encounters are more common under natural conditions than male monopolization of females because estimates of concurrent multiple paternity together with observations in a natural population do not favor mate guarding as the predominant mating strategy in this species. It follows from our study that the intensity of sexual selection on male size may be greatly overestimated when using a competitive laboratory setting for a species in which females generally encounter mates in a sequential fashion. Female remating probability was significantly predicted by female size, with large females remating with higher probability than small females. Thus, when mating with large females, males may gain higher fertilization success through increased female fecundity but also face a higher sperm competition risk. Copyright 2005.