Temperature-induced colour change varies seasonally in bearded dragon lizards

The benefits of colour change are expected to vary seasonally due to changes in reproductive activity, temperature and potentially predation risk; yet temporal variation in colour change has seldom been examined. We measured colour change in spring and autumn using captive individuals from two differently coloured populations of the central bearded dragon lizard, Pogona vitticeps. We predicted that colour change should be greater in spring than autumn due to added requirements of reproductive and territorial activity. To elicit colour change in a standardised way, we placed lizards inside temperature controlled chambers and measured colour at 15, 25, 35 and 40°C, repeating experiments in spring and autumn. Lizards from both populations changed from dark grey to light yellowish or orange-brown (increasing luminance and saturation) with increasing temperature in both seasons, and both populations changed colour to a similar extent. As predicted, the maximum extent of temperature-induced c...