Meeting Abstract
Because energy is the basic unit of physiological processes, understanding differences in energy usage may offer insight into selective pressures across physiological states. Gopherus polyphemus, Gopher Tortoise, has been shown to significantly alter immunity as a result of acclimation to winter dormancy, a pattern which is present across ectothermic vertebrate taxa. Herein, we were interested in assessing the metabolic consequences of winter acclimation in this species to determine if observed reduced immunity in dormancy confers a measurable level of energy conservation. We assessed oxygen (O2) consumption, carbon dioxide (CO2) production, and respiratory quotient (RQ; the ratio of CO2 production to O2 consumption) in G. polyphemus at two temperatures (12. 5°C and 32.5°C) and two seasonal acclimation states (winter and summer). We found that season did not have a direct effect on either O2 consumption or CO2 production, but that RQ was significantly elevated in animals at the colder temperature (P < 0.001). Additionally, we found very high RQs (> 1.0) in cold-acclimated animals during dormancy. The observed high RQs in this species are likely a result of anaerobic digestion occurring in the gut, as we documented significant anaerobic carbon dioxide production in fecal samples. Oxygen consumption was highest in animals at the warmer temperature, and the Q10 for O2 consumption in animals in this study was 2.34. While we failed to identify a reduced pattern of metabolism during dormancy, results from this study further demonstrate important physiological modulation between dormancy and activity in this species of conservation concern.
