Meeting Abstract
Thermal metabolic compensation is a well-established theory stating that ectotherms acclimated to a lower temperature will have a higher metabolic rate at a given temperature than those acclimated to a higher temperature. This partial compensation of MR increases overall fitness at low temperatures for these animals. When thinking about acclimatization, it is tempting to forget that the natural world is rarely at a constant temperature. This is especially true for desert environments that can easily see a range of 15-20 °C in a 24 hr period. Temperature change has far-reaching impacts on MR and exercise performance through changes in reaction rates and enzyme activity. In this study Grammastola rosea, a small tarantula endemic to the Atacama Desert, was used to investigate the implications of a fluctuating environment on SMR and carbon dioxide production during and after exercise. We used flow-through respirometry to examined standard metabolic rate (SMR) and MR during exercise at 15 °C and 30 °C following acclimation to 15 °C, 30 °C, and a treatment fluctuating between the two temperatures. As expected, the lower temperature acclimated spiders had a higher SMR than those acclimated to the higher temperature. However, the 15 °C spiders produced less CO2 during and after exercise than the 30 °C spiders. In the fluctuating treatment, spiders had an even higher SMR at both temperature than other treatments and had the highest CO2 production post-exercise at both temperatures. This study raises questions about the effects of acclimation to a fluctuating temperature on the overall physiology of the animals and has possible implications on the effect of climate change on small ectotherms.
