The genetic architecture of ovary size differences between Africanized and European honey bee workers

The evolution of reproductively specialized castes and social behavior from a solitary ancestor may be explained by the reproductive ground plan hypothesis.To test the generality of the hypothesized genetic linkage between reproductive and social behavior, we investigated the genetic architecture of ovary size differences between Africanized and European honey bees. Two backcrosses of a hybrid queen and Africanized drones that resulted in transgressive worker ovary phenotypes were studied for pleiotropic effects of existing behavioral QTL and potential new QTL with a combination of SNP and microsatellite markers. Analyses show small but significant effects on ovary size for some of the behavioral QTL, as predicted by the reproductive ground plan hypothesis. In addition, we detected two new QTL of major effect on ovary size. We describe potential candidate genes for the QTL and suggest that the detected major and minor effects could reflect genetic control of caste divergence and worker division of labor, respectively, representing two distinct stages of honey bee social evolution that may be connected via female reproductive physiology.