Association between Larger Ovaries and Pollen Foraging in Queenless Apis cerana Workers Supports the Reproductive Ground-plan Hypothesis of Social Evolution By: O. Rueppell,

Article: Introduction Based on the ovarian ground-plan hypothesis (West-Eberhard 1987; West-Eberhard 1996) the reproductive ground-plan hypothesis of social evolution has recently been proposed as a theoretical framework to understand social evolution in honeybees (Amdam et al. 2004, 2006). The reproductive ground-plan hypothesis seeks to explain the evolution of honeybee social complexity from solitary ancestors by co-option of control elements of the female, gonadotropic reproductive cycle (Amdam et al. 2004). One of its central predictions, therefore, is that reproductive physiology and social behavior, in particular division of labor, be linked in particular ways (Amdam et al. 2006). Ovary size influences the level of reproductive hormones (Goodman and Granger 2005) and is therefore predicted to be correlated with differences in social behavior. Honey bee workers exhibit agedependent division of labor between in-hive tasks and foraging (Beshers and Fewell 2001) but intrinsic worker differences affect the timing of behavioral transitions and further aspects of the division of labor, such as the specialization during foraging on nectar or pollen collection (Page and Erber 2002).