BIDIRECTIONAL SHIFTS IN COLONY QUEEN NUMBER IN A SOCIALLY POLYMORPHIC ANT POPULATION
Article first published online: 20 DEC 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 4, pages 1169–1180, April 2013
How to Cite
Purcell, J. and Chapuisat, M. (2013), BIDIRECTIONAL SHIFTS IN COLONY QUEEN NUMBER IN A SOCIALLY POLYMORPHIC ANT POPULATION. Evolution, 67: 1169–1180. doi: 10.1111/evo.12010
- Issue published online: 3 APR 2013
- Article first published online: 20 DEC 2012
- Accepted manuscript online: 21 NOV 2012 08:55AM EST
- Received April 9, 2012 Accepted October 8, 2012 Data Archived: doi 10.5061/dryad.6qd10
- parentage analysis;
- phenotypic plasticity;
- social evolution
The breeding system of social organisms affects many important aspects of social life. Some species vary greatly in the number of breeders per group, but the mechanisms and selective pressures contributing to the maintenance of this polymorphism in social structure remain poorly understood. Here, we take advantage of a genetic dataset that spans 15 years to investigate the dynamics of colony queen number within a socially polymorphic ant species. Our study population of Formica selysi has single- and multiple-queen colonies. We found that the social structure of this species is somewhat flexible: on average, each year 3.2% of the single-queen colonies became polygynous, and conversely 1.4% of the multiple-queen colonies became monogynous. The annualized queen replacement rates were 10.3% and 11.9% for single- and multiple-queen colonies, respectively. New queens were often but not always related to previous colony members. At the population level, the social polymorphism appeared stable. There was no genetic differentiation between single- and multiple-queen colonies at eight microsatellite loci, suggesting ongoing gene flow between social forms. Overall, the regular and bidirectional changes in queen number indicate that social structure is a labile trait in F. selysi, with neither form being favored within a time-frame of 15 years.