Abstract

In polygynandrous species, sperm competition and female post-insemination processes may influence male paternity success. Hence, insemination (i.e. successful sperm transfer) may not guarantee reproductive success for the male. Using a variation of Parker's (1970) sterile (irradiated) male technique, I examine the relationships among paternity success, mating success (proportion of matings resulting in sperm transfer) and duration of copulation for males of the polygynandrous waterstrider Aquarius remigis . Prolonged copulation is characteristic of this species and has been interpreted as a paternity assurance strategy, analogous to post-copulatory contact guarding. Mating success was a significant predictor of fertilization success for males. The results of this study lend strength to previous studies of sexual selection in A. remigis that have used mating success as an estimate of reproductive fitness. However, the presence of considerable unexplained variance in paternity success suggests that post-insemination processes may also be important. Copulation duration correlated negatively with mating success, suggesting a trade-off between mating frequency and duration. Contrary to expectations, copulation duration also tended to have a negative effect on paternity success. These results suggest that prolonged copulation is not analogous to post-copulatory contact guarding and does not function as a paternity assurance strategy in A. remigis .