STRONG SELECTION ON A GENE THAT INFLUENCES REPRODUCTIVE COMPETITION IN A SOCIAL INSECT

COMPETITION among nestmate females for reproductive opportunities is a fundamental property of insect societies, the outcome of which defines the form of colony social organization and the nature of subsequent social evolution 1-3. Several factors influencing the outcome of competition among potential reproductives have been identified in eusocial Hymenoptera, including age 4, size 5-7 and degree of ovary or exocrine gland development 7-10. In no case is the genetic basis of traits associated with success in these social contests understood, although there is a heritable component to their expression in laying worker honey bees 11. I report here the existence of a single mendelian factor that strongly influences success in reproductive competition in multiple-queen societies of an ant, and I also propose a mechanism by which variation is maintained at this gene despite the presence of strong directional selection.