For more than two decades, it has been the dogma that the males of pollinating fig wasps do not fight and that they only mate in their native fig. Their extreme degree of local mating leads to highly female biased sex ratios that should eliminate the benefits of fighting and dispersal by males. Furthermore, males sharing a fig are often brothers, and fighting may be barred by kin selection. Therefore, theory supported the presumed absence of fighting and dispersal in pollinating fig wasp males. However, we report here that in pollinating fig wasps, fighting between brothers evolved at least four and possibly six times, and dispersal by males at least twice. This finding supports the idea that competition between relatives can cancel the ameliorating effects of relatedness. The explanation to this evolutionary puzzle, as well as the consequences of male dispersal and fighting, opens the doors to exciting new research.
Fig wasp mating ecology is fascinating and has delivered textbook examples of skewed sex ratios resulting from local mate competition, and of alternative mating strategies. One or a few females of the pollinating species crawl into a fig to lay their eggs in the flowers on the inside of the fruit. The males hatch first and inseminate the females, mostly their sisters, inside the fig. Then the males chew a tunnel through the fig wall in order to release the females. The males are believed to be helpless on the outside of the fig and useless after the tunnel has been chewed [1,2]. They either die inside their natal fig or slip to the ground and their imminent deaths. This mating history leads to extreme local mate competition between brothers and as a result, mothers produce very female biased sex ratios . In this way, mothers can reduce futile competition between her sons. This reduction of the potential conflict between brothers as well as the fact that interacting males are related is believed to result in the absence of fighting in pollinating species .