Behaviour 2019
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Dealation activates the helper-like phenotype in a primitively-eusocial ant gyne
Benjamin C. Pyenson, Christopher Albin-Brooks, Juergen Liebig. Social Insect Research Group, School of Life Sciences, Arizona State University, Tempe, AZ, United States

            One of the major evolutionary transitions is the shift from solitary to eusocial life which is further followed by the evolution of morphologically-distinct castes of reproducers and helpers in many highly-eusocial insect species. Since a wing polyphenism, where some individuals develop wings while others do not, appears in some highly-social insects like termites, but not in others like honey bees, the role of dispersal polyphenisms in the evolution of eusociality in ants is unclear. By comparing primitively-eusocial ant gynes under alate and dealate conditions, we found that the loss of wings initiates the helper-like phenotype characteristic of ant workers. Not only do gynes show wing-dependent differences in chemical signaling, but dealate gynes also display helper-like reproductive hierarchy-forming behaviors which do not occur during colony foundation. Since gynes can activate the helper phenotype after wing loss, the essential difference between ant queen and worker castes is a dispersal polyphenism. Individuals with lower dispersal capacity might have benefited from helping in the colony, providing an early step in the evolution of ant eusociality.