Reproductive monopoly enforced by sterile police workers in a queenless ant
Source: Behavioral Ecology, Volume 15, Number 6, November 2004 , pp. 970-975(6)
Publisher: Oxford University Press
Abstract:In societies of totipotent insects, dyadic dominance interactions generate a hierarchy that often underlies an extreme reproductive skew. Subordinates remain infertile but can maximize their indirect fitness benefits through collective power (worker policing): interference with challenging high-rankers can prevent an untimely replacement of the reproductive. However, police workers only benefit if they favor individuals with high fertility. In the monogynous queenless ant Streblognathus peetersi, we used behavioral, physiological, and chemical methods to show that police workers have the primary role in the selection of the reproductive, and that they probably use reliable information about fertility encoded in the cuticular hydrocarbons to make their decision. We successfully decreased an alpha's fertility by using a hormonal treatment (Pyriproxyfen, a juvenile hormone analogue), and she was always removed from the hierarchy by police workers. In the preceding days, one of the high-rankers became aggressive, although her interactions were not directed at the treated alpha. All treated alphas (n = 10) remained aggressive but ended up immobilized by low-ranking workers after a median time of 11.5 days. By then, the challenging high ranker exhibited dominance behaviors typical of the alpha rank. In parallel, the cuticular profile of the treated alpha exhibited predictable and opposite modifications to that of the challenger's. This is the first study that uncouples dominance and fertility in a social insect: it gives a better understanding of the crucial role of sterile helpers in the control of reproductive skew in animal societies.
Document Type: Research article
Affiliations: 1: Laboratoire d'Écologie, CNRS UMR 7625, Université Pierre et Marie Curie, 7 quai St Bernard, 75005 Paris, France, and 2: Institut de Recherche sur la Biologie de l'Insecte, CNRS UMR 6035, Faculté des Sciences, Parc de Grandmont, 37200 Tours, France
Publication date: 2004-11-01
- Bringing together significant work on all aspects of the subject, Behavioral Ecology is broad-based and covers both empirical and theoretical approaches. Studies on the whole range of behaving organisms, including plants, invertebrates, vertebrates, and humans, are included.