Meeting Abstract

P2.196  Monday, Jan. 5  Effects of winter temperature on the energetics and hydration of lizards ZANI, P.A.**; COUNIHAN, J.L.; FRIED, B.; SHERMA, J.; Lafayette College; Lafayette College; Lafayette College; Lafayette College zanip@lafayette.edu

Global climate change has the potential to increase winter temperatures, resulting in higher winter metabolic rates of ectotherms, and thus, altering energetic requirements for survival. To test the impacts of winter temperature on survival of ectotherms, we subjected side-blotched lizards (Uta stansburiana) to relatively warm (8 C) or cold (1 C) winter conditions for up to 149 d. As in previous experiments, animals in the cold survived longer than those in warm winter conditions. As lizards died naturally we quantified neutral lipids using HPTLC of the liver, fat body, and tail as well as carcass moisture content. We also euthanized lizards as controls during the experiment. Results indicate that animals that died naturally lost significantly more mass than controls with a marginal temperature trend (warm treatment lost more mass than cold). However, organ masses were not related to temperature or type of death (natural/control). Furthermore, percentages of triacylglycerol (TG) in fat bodies and tails were not different in animals exposed to warm or cold temperature, but animals in the cold had higher levels of liver TG than animals in the warm treatment. Thus, only liver TG appears to be affected by winter temperature. Yet, there was no difference in liver TG between natural death and control animals suggesting that lack of TG was not the cause of death. When we compared moisture content of animals we found that those exposed to a warm winter contained less water at death than those exposed to the cold. Furthermore, animals that died naturally contained significantly less moisture than controls. These results suggest that the primary effects of winter temperature in these lizards are on hydration rather than energetics and that water loss is the main cause of winter mortality.