Meeting Abstract

S10.11  Friday, Jan. 7  Thermal ecology of a diurnal desert rodent LEVY, Ofir; DAYAN, Tamar; KRONFELD-SCHOR, Noga*; Tel Aviv University; Tel Aviv University; Tel Aviv University nogaks@tauex.tau.ac.il

We studied the relationship between the order of arrival to a food patch, food consumption and thermoregulatory strategy, and the effect of food supplementation during summer and winter on thermoregulatory strategy, in a diurnal desert rodent, the golden spiny mouse (Acomys russatus) in semi-natural field conditions. The order of foraging in the patches had a negative effect on the amount of food consumed: earlier foragers had access to more food. Daily time spent torpid was related to the order of arrival to the food patch; earlier foragers spending less time torpid. Daily time spent torpid decreased as individuals increased daily food consumption, and was negatively correlated with Ta. Time spent torpid was positively related to body mass. We also found that under natural food availability spiny mice thermoregulated more precisely during summer than during winter. They spent more time torpid during summer than during winter even when food was supplemented (although summer nights are shorter), allowing them to conserve water. Supplementing food resulted in more precise thermoregulation in both seasons, and mice spent less time torpid. In summer, thermoregulation at high ambient temperatures was less precise, resulting in higher maximum body temperatures in summer than in winter, also when food was supplemented, in accord with the expected effect of water shortage on thermoregulation. Our results suggest that, as expected, precise thermoregulation is beneficial when possible and is abandoned only when the costs of homeothermy outweigh the benefits. Furthermore, they indicate that thermoregulatory strategy is affected by ecological interactions, specifically resource-mediated intraspecific competition.