Food, temperature and endurance: effects of food deprivation on the thermal sensitivity of physiological performance

作者：Gilbert Anthony L^*; Miles Donald B

来源：Functional Ecology, 2016, 30(11): 1790-1799.

DOI：10.1111/1365-2435.12658

• climate change
• food limitation
• locomotor performance
• resource availability
• thermal optimum
• thermal performance curve

Studies of thermal ecology and physiology (e.g. the change in performance with temperature) provide critical data for predicting the potential responses of ectothermic organisms to climate change. Projected modification of current ambient temperature in the future is expected to result in shifts in whole-organismal performance, which could lead to a diminishment in individual fitness, resulting in demographic collapse. The anticipated responses of ectothermic organisms to climate change focus on the direct effects of temperature and neglect other potential concomitant changes to the environment. Climate models forecast dramatic alteration in precipitation patterns, which in some regions will lead to prolonged drought. Rising temperatures coupled with decreased rainfall will disrupt patterns of net primary productivity and as a consequence alter the prey base and seasonal food availability. Individuals exposed to lower food availability are expected to adjust thermoregulatory behaviour to reduce their daily energetic expenditures. The consequences of fasting in lizards have received scant attention; consequently, we examined the effects of alteration in food availability on both preferred body temperatures in a thermal gradient and the thermal sensitivity of locomotor performance in the lizard Urosaurus ornatus. We experimentally manipulated food access to two groups of lizards and compared thermal preference and thermal performance curves. We found distinct shifts in preferred body temperature and locomotor performance when food availability is restricted. Fasted lizards exhibited reduced preferred body temperatures compared to fed lizards. The position and shape of thermal performance curves differed between fasted and fed lizards. Fasted lizards had lower optimal temperatures of performance and wider thermal performance breadths than fed lizards. Restricted access to food resources leads to thermal biological patterns favouring lower temperatures. Lizards with low food access may be restricted to shaded regions of their habitat, unable to cope with the stressful situation of activity at warmer temperatures, and thus be at a selective disadvantage for procuring energetic or reproductive opportunities. By characterizing the interaction between thermal physiology and food availability, our study provides more clarification regarding the bioenergetic pressures likely to affect lizards in warmer environments.

• 出版日期2016-11