The scent of inbreeding: male sex pheromones betray inbred males

Inbreeding depression results from mating among genetically
related individualsand impairs reproductive success. The
decrease in male matingsuccess is usually attributed to an
impact on multiple fitness-related traitsthat reduce the general
condition of inbred males. Here, we find that the productionof
the male sex pheromone is reduced significantly by inbreeding
inthe butterfly Bicyclus anynana. Other traits indicative
of the general condition,including flight performance, are also
negatively affected in malebutterflies by inbreeding. Yet, we
unambiguously show that only the productionof male pheromones
affects mating success. Thus, this pheromonesignal
informs females about the inbreeding status of their mating
partners.We also identify the specific chemical component,
hexadecanal, probablyresponsible for the decrease in male
mating success. Our results advocategiving increased attention
to olfactory communication as a major causalfactor of
mate-choice decisions and sexual selection.Published in the
Proceedings of the Royal Society of London (2013) in press.