Document Type


Publication Date



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


Ants greatly influence ecosystems; thus, it is important to address how the current issue of global warming may be affecting ants. We investigated the effect of various temperatures on the metabolic rates of two species of Harvester ants, Pogonomyrmexcalifornicusand P. barbatus. We hypothesized that ants from a hotter than average region will have a higher optimal performance temperature, and thus the rate of oxygen consumption at higher temperatures than ants from cooler regions. Thus, ants from hotter regions were expected to reach their peak in performance activity at higher temperatures. Therefore, we predicted that P. californicus, from California, would have an optimal performance temperature that is greater than. barbatus, from Utah. P. californicus, which has an estimated optimal performance temperature of about 40-45°C, has a higher optimal performance temperature than the P. barbatus, which has an optimal performance temperature of about 25°C. Additionally, the P. californicus rate of oxygen consumption was stable at temperatures at which the P. barbatus reached its critical limit, suggesting that the P. californicus can be active at a broader range of temperatures.