Biotic and abiotic controls of Argentine ant invasion success at local and landscape scales

• Published in: Ecology (Durham) 2007-12, Vol.88 (12), p.3164-3173
• Main Authors: Menke, S. B., Fisher, R. N., Jetz, W., Holway, D. A.
• Format: Article
• Language: English
• Subjects: abiotic factors; abiotic stress; Animal and plant ecology; animal stress; Animal, plant and microbial ecology; Animals; ant; Ants; Ants - growth & development; Ants - physiology; Argentina; Biological and medical sciences; Biological invasions; biotic resistance; Climate change; colonizing ability; Conservation of Natural Resources; Ecological invasion; Ecosystem; Experiments; field experimentation; Formicidae; Fundamental and applied biological sciences. Psychology; General aspects; geographic information systems; GIS; indigenous species; Insect colonies; Insect ecology; Insect pests; Insects; interspecific competition; Introduced species; invasion; Invasive species; irrigation; Landscapes; Linepithema humile; Population Density; Population Dynamics; precipitation; provenance; Rain; Resistance to control; scale; Seasons; spatial data; Species diversity; stress tolerance; Temperature; winter
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/07-0122.1

Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies—especially on animals—have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combained native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants showed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native and species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitions in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where introduced species will occur and how their range limits may shift as a result of climate change.