Altered Social Behavior and Success of Invasive Species

Biological invasions are a serious threat to global biodiversity, and much of our research is focused on a particularly damaging invader, the Argentine ant (Linepithema humile). Argentine ants have been introduced by humans to many of the world's Mediterranean-type ecosystems, where they disrupt ecosystems by displacing native species, cause indirect damage to crops by tending parasitic homoptera (such as aphids and scale insects), and are a common household pest. Moreover, introduced populations of Argentine ants are unicolonial, forming massive "supercolonies" that can extend for thousands of kilometers. The lack of aggression and territoriality within these supercolonies allows introduced populations to thrive and dominate invaded habitats. By studying the genetics and behavior of Argentine ants in their native and introduced ranges, we have shown how relatively simple genetic changes can impact higher levels of biological organization, producing altered behavior, novel forms of social organization, and ultimately transforming entire ecosystems. Because many other invasive ants are also unicolonial, the factors that allow Argentine ants to become such successful invaders may also explain the success of many other invasive social insects.