From a colony to an empire! Population structure of the little fire ant, Wasmannia auropunctata, in ecological life zones of Puerto Rico

The transport of organisms by humans to new ecosystems where they become non-natives or exotic species is common. Many of these introduced organisms become invasive, and represent a worldwide concern. Not all introduced organisms are successful invaders. Ultimately, the success of introduced invasive species can be in part due to pre-adaptations and lack of competitors and enemies. Although invasive organisms tend to cause detrimental effects, they can be considered important models for studying population dynamics, due to their rapid adaptations and success. One of the most successful invasive ants in the world is the little fire ant (Wasmannia auropunctata), which was introduced to the tropical island of Puerto Rico over a hundred years ago. In this study, we will evaluated population structure between ecological life zones of the island and heterozygosity of the W. auropunctata population through microsatellites. We found that there is one population and high heterozygosity throughout  Puerto Rico. Our data suggest that there is no population structure between the ecological life zones and high heterozygosity when compared with data from French Guiana. Our results are similar to recent studies of Africanized honey bees (Apis mellifera), in Puerto Rico, which suggest a single invasion with a fast spread throughout the island and after over 15 years of invasion there is no apparent population structure as determined by microsatellite analysis. The results of this study should expand our understanding of the evolution and success of this ant as an invasive species.