In ants, the evolution of the most complex societies is connected to limited dispersal. Especially supercolonial ants that live in the biggest societies with lowest relatedness, have highly philopatric queens. However, the underlying causal mechanisms are still poorly understood. My research focuses on the interplay of dispersal evolution and social evolution in socially polymorphic Formica ants.In some of the Formica species all daughter queens disperse and found new independent colonies, whereas in others a large majority of them stays in their natal colonies as extra queens, resulting in supercolonial societies.
I measured dispersal-related traits, such as flight muscle size, the microscopical structures of the muscles, and overall metabolic resources, to inspect the dispersal ability of young males and daughter queens in six Formica species with varying social organizations. According to my results the supercolonial species do not have consistently weaker queen dispersal traits than the non-supercolonial species, which indicates the increased queen philopatry in supercolonial species is foremost a behavior trait. However, I observed a small decrease of male flight muscle ratio in supercolonial species, showing the males have evolved to be more philopatric in accordance to the queens. Next, I focused on the behavior of young queens and workers at the onset of dispersal insupercolonial F. aquilonia. The young queens of this species often drop their wings in their natal colonies, showing their reluctance to disperse. According to my results the workers actively kill a proportion of these young queens, possibly to limit the number of queens they allow to stay in the colony. Such a costly behavior implies that there may be an unresolved conflict over dispersal in these societies.