Ants live in complex social colonies in which each individual has a well-defined role, but the mechanisms by which this interaction is maintained remains unclear. In January 11 Science, Michael Krieger and Kenneth Ross from University of Georgia, Athens, USA show that a single gene can control complex behavior patterns important in colony formation and social evolution.

Krieger & Ross discovered that the Gp-9 gene of the South American fire ant (Solenopsis invicta) encodes a pheromone-binding protein that is essential for chemical recognition of conspecifics. In addition, analyses of sequence evolution of Gp-9 suggest that positive selection has driven the divergence between the alleles associated with alternate social organizations (Science 2002, 295:328-332).

"The greatest significance of this work is it demonstrates that alternations or variations in social behavior within a species can very profoundly influence patterns of interbreeding," said Ross, an entomologist. "It suggests that...