The colony structure and population biology of invasive ants

Ants are among the most widespread and damaging of introduced species. Many invasive ants share a suite of characteristics that facilitate their introduction, establishment, and subsequent range expansion. One feature of particular importance is the ability to form numerically large, ecologically dominant colonies. We review the population biology of invasive ants, focusing on the role of sociality and colony structure in their success. Specifically, we considered different hypotheses that have been proposed for the observed transitions in social structure of the two most well-studied ant invaders, the Argentine ant ( Linepithema humile ) and the red imported fire ant ( Solenopsis invicta ). In both species, genetic changes during or subsequent to introduction have led to alterations in social behavior and colony structure; these, in turn, have promoted the invasive success of introduced populations. Although many other invasive ant species appear to have similar forms of social organization, little is known about the basic population biology of these species.