Selected Body Temperature in Diurnal and Nocturnal Forms of Ptyodactylus (Reptilia: Gekkoninae) in a Photothermal Gradient

Abstract

The three Israeli forms of Ptyodactylus (P. hasselquistii puiseuxi, P. h. guttatus and P. h. hasselquistii) differ in daily activity pattern, being mainly diurnal, diurno-nocturnal and nocturnal, respectively. We measured body temperatures of the three forms in a photothermal gradient. They differed significantly from each other in mean selected body temperature, the northern, diurnal P. h. puiseuxi having the highest value of 33.5 .+-. 1.5.degree.C, the southern, nocturnal P. h. hasselquistii having the lowest values of 28.7 .+-. 1.7.degree.C, and the common, diurno-nocturnal P. h. guttatus having an intermediate mean selected body temperature of 30.9 .+-. 2.4.degree.C. Frequency distributions of body temperatures revealed modes of 35.degree.C in P. h. puiseuxi, and 28.degree.C in P. h. hasselquistii, and a bimode of 30.degree.C and 34.degree.C in P. h. guttatus, P. h. hasselquistii chose significantly lower ambient temperatures and had a significantly wider range of body temperatures compared with P. h. guttatus. The diurnal P. h. puiseuxi maintained a significantly greater body-to-air temperature difference than both other forms. We concluded that the selected body temperatures of the three forms are closely associated with their different daily activity patterns and with their distinct ecological distributions.