REPRODUCTIVE CONFLICT AMONG ANT WORKERS IN DIACAMMA SP FROM JAPAN - DOMINANCE AND OVIPOSITION IN THE ABSENCE OF THE GAMERGATE

Queens do not exist in Diacamma sp. from Japan, and a single worker (' 'gamergate'') mates and monopolizes reproduction in each colony. We is olated small groups of workers without the gamergate, and confirmed th at after 7-15 days many workers were able to oviposit (Tab. 1). These egg-laying individuals engage in stereotyped attacks towards each othe r. In six groups of individually marked workers (Tabs. 3 to 7), the pa ttern of aggressive interactions always indicated that one worker was dominant. She usually initiated a large number of attacks, but was her self never attacked. This dominant worker (''alpha'') also ate the egg s just laid by others. There was no linear dominance hierarchy, althou gh a second highest-ranking worker could be recognized (she was only a ttacked by alpha). When these workers were dissected 4-6 weeks after b eing orphaned, only the alpha worker had active ovaries, other individ uals that had been observed to oviposit earlier exhibited resorbed ova ries. Dissection of another 12 orphaned groups, kept together for diff erent periods of time (Tab. 2), confirmed that one dominant worker is able to suppress the ovarian activity of all others in her group. We d iscuss how these aggressive interactions also function to regulate the production of males in other contexts, even when the gamergate is pre sent. This aggression is separate. however, from another competitive i nteraction, mutilation of the gemmae, that functions as a control of m ating activity in this species.