Effects of temperature on maximum clinging ability in a diurnal gecko: evidence for a passive clinging mechanism?

The thermal dependence of performance of ectotherms, and particularly locomotor performance in lizards, has received much attention. However, only a single study has examined the effects of temperature on adhesive clinging ability in geckos, despite the importance of adhesion for many pad-bearing lizards and invertebrates. We set out to characterize the thermal response of clinging ability in the diurnal gecko, Phelsuma dubia in the temperature range of 15-35 degrees C. Our findings indicate that there is no significant trend in clinging ability for P. dubia with temperature and that there is high variation about the mean at all temperatures. These findings differ from other whole-organism studies of clinging performance and are suggestive of a passive clinging mechanism that is dominated by intermolecular van der Waals forces. These findings also suggest that clinging ability in this species is not under selective pressures resulting from thermal variation, and that P. dubia does not need to regulate body temperature closely to maximize clinging ability.