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Pogonomyrmex californicus, Pogonomyrmex barbatus, invasive species, climate change, respiration, optimum performance, performance curve, Bernard Field Station


Linepithema humile is an invasive species that successfully inhabits environments worldwide. Its success in exploiting a wide range habitat may relate to its ability to modify thermal performance in different habitats. We examined the temperature dependence of running speed for L. humile from two different microhabitats at the Robert J. Bernard Biological Field Station in Claremont, California. We hypothesized that L. humile would exhibit similar running speeds in both microhabitats, and that running speeds would increase with temperature until 40 °C. We found a positive correlation between temperature and running speed in the woodland habitat and a negative correlation between temperature and running speed in the non-native grassland habitat. No foraging behavior was observed at 56.1 °C and 50 °C in the woodland habitat and the non-native grassland, respectively. Foraging activity occurred at temperatures that exceeded 40°C. We were unable to demonstrate that L.humile exploits different temperature ranges to inhabit different ecosystems.

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