Lower selected body temperatures after food deprivation in the lizard Anolis carolinensis

Diet composition can affect body temperatures selected by lizards in a thermal gradient (SBT) but there is very little evidence to support a similar effect due to fasting. The latter could represent a means of energy conservation during periods of low food availability. This study investigated the impact of short-term food deprivation (5 days) on diurnal thermal preferences of male (n=10) and non-reproductive female (n=22) Anolis carolinensis using a repeated measures design. Mean SBT varied significantly over the 4 h measurement period, and was higher for males than females, overall. A small but significant change in SBT was detected between the two feeding treatments, with food deprivation leading to a mean decrease ranging from 0.43±0.55 to 0.72±0.46 °C (at different times of day) in females and from 0.61±0.71 to 2.13±0.76 °C in males. Previous studies may have failed to detect such subtle trends due to a lack of statistical power arising from small sample sizes. An explanation of these differences is they represent a feeding status dependent trade-off for maintenance of energy balance versus optimal food assimilation. However, (1) the estimated energy saving, and (2) the impact on food assimilation appear rather negligible even assuming that the observed decrease in SBT produces a similar lowering of field body temperature in the wild.