Polygyne

Polygyne is a phenomenon occasionally observed in ant colonies. These colonies have multiple queens, whereas for most ant species, colonies are monogyne, having only one queen. Physiology and behavior of queens between these two colony structures differ greatly. Queens in polygyne colonies are smaller and generally have fewer energy reserves than those in monogyne colonies. The large energy reserves of queens in monogyne colonies are used for extended flights in which the queen leaves the ant colony in search of mates. Males from monogyne colonies swarm from the nest for mating and foundation of new colonies with a new monogyne queen. A monogyne queen will produce far more offspring during her lifetime than a polygyne queen. Polygyne queens produce few offspring and rarely travel far from the natal nest1.

The red imported fire ant, Solenopsis invicta, is an invasive species of which both monogyne and polygyne colonies have been observed. Evidence suggests that determination of this trait is genetic, determined by the Gp-9 gene. Monogyne queens are homozygous with both dominant forms of the allele (BB), and polygyne queens being heterozygous (Bb)2. Polygyne colonies are extremely successful invaders compared with monogyne colonies and allow for the formation of supercolonies in the territory in which it is introduced. Increased frequency of polygyne colonies in the U.S. compared with the fire ant's native range has been attributed to the genetic bottleneck that occurred during its introduction. This trait has greatly contributed to the success of S. invicta as an invasive species3.

References:

1Goodisman, M.A.D., C.J. DeHeer and K.G. Ross. Unusual behavior of polygyne fire ant queens on nuptial flights. Journal of Insect Behavior 13(3): 455-468.

2Valles, S.M. and S.D. Porter. 2003. Identification of polygyne and monogyne fire ant colonies (Solenopsis invicta) by multiplex PCR of Gp-9 alleles. Insectes Sociaux 50(2): 1999-2000.

3Tsutsui, N.D., A.V. Suarez, D.A. Holway and T.J. Case. 2000. Reduced genetic variation and the success of an invasive species. Proceedings of the National Academy of Sciences 97(11): 5948-5953.