PARENT SESSION
Contributed Oral Session 47: Invasive Species: Environmental and Habitat Factors
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Abiotic factors control invasion by ants at the community scale.
Menke, Sean*,1, Holway, David1, 1 University of California-San Diego, La Jolla
ABSTRACT- Environmental conditions are often considered the most important factor in predicting the global spread of invasive species. But, fine-scale variation in the physical environment is often ignored as a causal mechanism of community susceptibility to invasion. It has long been suspected that Argentine ant (Linipithema humile) invasion success is limited by environmental suitability. In this study, the direct and indirect role of abiotic conditions was examined with regard to the ability of Argentine ants to invade native communities. Argentine ants invaded previously resistant native communities under a regime of experimentally elevated soil moisture. They successfully spread despite increased native ant activity in irrigated transects. Increased abundance facilitates the ability of L. humile to displace native ants and spread into natural habitats. Linipithema humile abundance increased as a direct result of elevated soil moisture levels in a series of field experiments. Increased levels of soil moisture also caused plants to flourish, which indirectly contributed to the spread of L. humile. Plant growth provided Argentine ants with increased levels of shade, further ameliorating environmental conditions, and increased food resources. Argentine ants increased in abundance when water was added, even when plant growth was suppressed, arguing for the direct and important effect of soil moisture. This work allows us to predict future sites of invasion and to manage xeric habitats under the threat of invasion. These results are a rare experimental demonstration of the importance of fine-scale heterogeneity in the physical environment as a factor influencing whether animal invasions succeed.
Key words: Argentine ants, Linipithema humile, Biological Invasion, Abiotic factors