Current address: CIRAD BIOS UR-106, Acridologie, TA A-50/D, Campus de Baillarguet, 34398 Montpellier cedex 5, France.
SEXUAL SELECTION WITHOUT SEXUAL DIMORPHISM: BATEMAN GRADIENTS IN A SIMULTANEOUS HERMAPHRODITE
Article first published online: 15 NOV 2011
© 2011 The Author(s). Evolution © 2011 The Society for the Study of Evolution.
Volume 66, Issue 1, pages 66–81, January 2012
How to Cite
Pélissié, B., Jarne, P. and David, P. (2012), SEXUAL SELECTION WITHOUT SEXUAL DIMORPHISM: BATEMAN GRADIENTS IN A SIMULTANEOUS HERMAPHRODITE. Evolution, 66: 66–81. doi: 10.1111/j.1558-5646.2011.01442.x
- Issue published online: 3 JAN 2012
- Article first published online: 15 NOV 2011
- Accepted manuscript online: 11 AUG 2011 11:25AM EST
- Received November 24, 2010, Accepted July 14, 2011
- Freshwater snail;
- mating success;
- opportunity for selection;
- reproductive success;
- selection gradients;
- sex correlations
One of the most general patterns in sexual selection is stronger selection on mating activity in males than in females. This asymmetry is thought to result from the higher energetic cost of producing one female compared to one male gamete (anisogamy). However, most studies focused on gonochoric species with strong sexual dimorphism, in which males and females are necessarily under different selection regimes. The question remains whether anisogamy alone would suffice to produce such differences. In simultaneous hermaphrodites one can compare sexual selection on the male and female functions in the absence of sexual dimorphism. Here we quantify sexual selection in the hermaphroditic freshwater snail Physa acuta under laboratory conditions. We combine exhaustive behavioral records of mating activity in mating groups and molecular paternity assignment to measure the mating success and reproductive success of 120 individuals. Our results validate the prediction of stronger selection to gain mating partners in the male than in the female function. Moreover, we did not detect cross-sex effects on fitness, or correlations between male and female production of offspring over the course of our experiment. We conclude that with respect to sexual selection P. acuta is comparable to gonochorists, confirming that anisogamy is a sufficient explanation for the differences in sexual selection regimes between sexes.