A crucial question in sexual selection theory is whether post-copulatory sexual selection reinforces or counteracts conventional pre-copulatory sexual selection. Male body size is one of the traits most generally favoured by pre-copulatory sexual selection; and recent studies of sperm competition often suggest that large male size is also favoured by post-copulatory sexual selection. In contrast to this general pattern, this study shows that pre-and post-copulatory sexual selection act antagonistically on male body size in Gerris lacustris. One large and one small male were kept together with two females in this experiment. Large males had a signi¢cant mating advantage, but small males copulated longer and gained higher fertilization success from each mating. Large and small males, however, gained similar reproductive success, and there was no overall correlation between mating success and reproductive success. These results suggest that estimates of male ¢tness based solely on mating success should be viewed with caution, because of potentially counteracting post-copulatory selection.

Recent theoretical and empirical interest in postmating processes have generated a need for increasing our understanding of the sources of variance in fertilization success among males. Of particular importance is whether such postmating sexual selection merely reinforces the effects of premating sexual selection or whether other types of male traits are involved. In the current study, we document large intraspecific variation in last male sperm precedence in the water strider Gerris lateralis. Male relative paternity success was repeatable across replicate females, showing that males differ consistently in their ability to achieve fertilizations. By analyzing shape variation in male genital morphology, we were able to demonstrate that the shape of male intromittent genitalia was related to relative paternity success. This is the first direct experimental support for the suggestion that male genitalia evolve by postmating sexual selection. A detailed analysis revealed that different components of male genitalia had different effects, some affecting male ability to achieve sperm precedence and others affecting male ability to avoid sperm precedence by subsequent males. Further, the effects of the shape of the male genitalia on paternity success was in part dependent on female morphology, suggesting that selection on male genitalia will depend on the frequency distribution of female phenotypes. We failed to find any effects of other morphological traits, such as male body size or the degree of asymmetry in leg length, on fertilization success. Although males differed consistently in their copulatory behavior, copulation duration was the only behavioral trait that had any significant effect on paternity.

Prolonged and severe dyspareunia is a great health problem among all women and especially young women, for whom a rising incidence of dyspareunia is suggested and discussed. Surprisingly few women have consulted a physician, raising the question of why this is the case and what can be done about it.

Four months' treatment with electromyographic biofeedback and topical lidocaine gave statistically significant improvements on vestibular pain measurements, sexual functioning, and psychosocial adjustments at the 12-month follow-up. No differences in outcome between the two treatments were observed but a larger sample may be needed to obtain significance. The treatments were well tolerated but the compliance to the electromyographic biofeedback training program was low. A combination of both treatments could potentially benefit many women with vulvar vestibulitis.