laevis in Cole et al. 1992) selleck products varied between sites, and among the three millipede species that we collected, two introduced species were slightly to much more abundant within invaded plots while an endemic species

was nearly absent in invaded plots. Beetles are often heavily armored (at least as adults), yet were among the most vulnerable species, while some groups possessing relatively thin exoskeletons (e.g., some Hemiptera and Collembola) fared better. It may be that few traits will accurately predict vulnerability across such a wide phylogenetic range, and that analyses must examine more specific traits within narrower taxonomic groups to yield better results. These traits could be morphological, physiological or behavioral, and could include such AMN-107 factors as the production of honeydew or defensive compounds, or behaviors that shelter species from ant activity. Although the examination of more specific intrinsic traits may be helpful, the high rates of variability shown in Tables 3 and 4 imply that there is a clear limit to the explanatory power of intrinsic traits. Species that had populations at multiple sites often exhibited strongly different patterns with respect to ant invasion among those sites, suggesting that extrinsic factors are responsible for

the differences. One potential extrinsic factor, ant density, was not a significant explanatory factor for species vulnerability, at least within the range of densities observed here. Similarly, population-level buy Gemcitabine variation in impact was not any greater when two sites were invaded BCKDHB by different ant species as compared to when they were both invaded by the same ant species, indicating that in this study system the identity of the invading ant was not an important factor. Instead, it seems likely that the specific community composition at each site

determines to a large extent the outcomes of many species. For example, endemic detritivores and herbivores may experience direct mortality from ant predation, but may also experience release from other predators that decline when ants invade. As a result, the net effect will depend on the strength of predation by ants relative to that of the predators they replace, along with other direct and indirect food web interactions that may be influential (Krushelnycky 2007). Without a closer examination of such interactions, it may not be possible to produce accurate predictions for many endemic herbivore and detritivore species. The high degree of variability in response to ant invasion in this system, among both species of the same order and populations of the same species, illustrates why previous attempts to identify higher taxa (e.g., families, orders) consistently vulnerable to invasive ants across studies and sites have encountered difficulties (Human and Gordon 1997; Holway et al. 2002).