Are native and exotic species fundamentally different? Do they interact with ecosystems differently? Should evolutionary history or native status be taken into account in studies of ecological theory? These are reasonable possibilities given that to become an established exotic, species must pass through selective pressures native species do not (e.g. transportation by humans). Many studies have asked these questions by looking for characteristics that make an organism a good invader. Instead, this study examines differences in native and exotic plant community interactions using a prevalent invasive species, Argentine ants (Linepithema humile) as an impartial resource seeker. Argentine ants are native to the Paraná River in South America. They directly use plants for nectar, and indirectly by harvesting aphid honeydew and as hunting arenas. In study sites in the San Francisco Bay area of California, USA, almost all invasive plants were from Europe or Asia and had no shared evolutionary history with Argentine ants. Argentine ant use of plants was quantified by examining all plants in plots surrounding ant nests over time to determine which plants Argentine ants and aphids used or ignored and with what intensity.
Results/Conclusions
Preliminary results show that Argentine ants use both native and exotic species of trees, shrubs, and forbs, and their use of plants changes over time. Thus far, it does not appear that native or exotic plants provide different resources to the community as groups. Instead, plant species appear to differ idiosyncratically in resource contribution to the community independent of origin. In conclusion, native and exotic plants appear fundamentally similar in their interactions within a community, lending support for testing theories of general community ecology using invasive species.