Studies of introduced species are often unable to eliminate alternative hypotheses explaining what makes a successfully invader because of both the vast distances and differences between native and invasive ranges.  Human modification to the environment in the forms of urban sprawl and agricultural have dramatically transformed the landscape.  Some native species have moved into these altered landscapes from adjacent natural areas, thereby becoming “native invasives”.  The odorous house ant (OHA) (Tapinoma sessile) has been recognized as a urban structural pest for over 100 years, is the most widespread native ant and pest ant in the US, and it is rapidly spreading its range as an urban pest.  Pest populations of the OHA share several life history traits (e.g. dominant behavior, unicoloniality, and polygyny) with many of the most destructive invasive ant species.  Interestingly, populations of the OHA in natural environments show genetic variation across their range at the mitochondrial Cytochrome Oxidase I (COI) gene and different life history traits including variation in dominance, colony size, and colony structure.  
Results/Conclusions

Here were determine, (1) the genetic differences of the OHA across its range and between urban and natural environments, and (2) the source environment for the urban pest populations using the COI gene.   Our results establish the use of the OHA and more generally other native pest species as a new model system to understand the mechanisms underling the success of introduced species.  Using these “native invasive” systems we can directly test and eliminate the alternative hypotheses that have been proposed to explain what makes a successful invasive species.