Couverture de Proceedings of the Royal Society of London

Cover image
A male of the Squinting Bush Brown butterfly (Bicyclus anynana) perching on a leaf in Limpopo, South Africa. In this species, females are unlikely to mate with inbred males. However, the paper by Erik van Bergen et al., in this issue of Proceedings B, shows that when females are unable to detect male sex pheromones their avoidance of inbred males disappears completely. (Photo by Erik van Bergen © used with permission.).

Erik van Bergen, Paul M. Brakefield, Stéphanie Heuskin, Bas J. Zwaan and Caroline M. Nieberding
The scent of inbreeding: a male sex pheromone betrays inbred males
Proc. R. Soc. B. 2013 280 20130102; doi:10.1098/rspb.2013.0102 (published 6 March 2013)

Abstract
Inbreeding depression results from mating among genetically related individuals and impairs reproductive success. The decrease in male mating success is usually attributed to an impact on multiple fitness-related traits that reduce the general condition of inbred males. Here, we find that the production of the male sex pheromone is reduced significantly by inbreeding in the butterfly Bicyclus anynana. Other traits indicative of the general condition, including flight performance, are also negatively affected in male butterflies by inbreeding. Yet, we unambiguously show that only the production of male pheromones affects mating success. Thus, this pheromone signal informs females about the inbreeding status of their mating partners. We also identify the specific chemical component (hexadecanal) probably responsible for the decrease in male mating success. Our results advocate giving increased attention to olfactory communication as a major causal factor of mate-choice decisions and sexual selection.