Thermal ecology of the Pygmy Alligator Lizard, Gerrhonotus parvus Knight and Scudday, 1985 (Squamata: Anguidae), in Nuevo Leon, Mexico

Temperature is one of the most important abiotic factors that affect organisms, and is perhaps the most acute of all. This study investigates the thermal ecology of the Endangered lizard Gerrhonotus parvus in Nuevo Leon, Mexico. The average body temperatures (T-b) of adult males and females (24.72 +/- 0.79 degrees C and 24.10 +/- 1.00 degrees C, respectively) were not significantly different (F1,43 = 0.21, p = 0.64); and those obtained in the spring and summer (24.50 +/- 0.58 degrees C and 25.59 +/- 1.38 degrees C, respectively) were not significantly different (F-2,F-49 = 0.66; p = 0.51). The body temperature presented positive and significant relationships with both air temperature (T-a; R-2 = 0.29, p < 0.05; T-b = 0.55 T-a + 12.52) and surface temperature (T-s; R-2 = 0.52, p < 0.05; T-b = 0.68 T-s + 8.07). The slope values in the regressions of Tb with air temperature (T-a) and substrate temperature (T-s) were 0.55 and 0.68, respectively. These results suggest that this small lizard is thigmothermic and depends more on the temperature of the substrate (T-s) than the temperature of the air (T-a) to passively regulate its body temperature. In this way, Gerrhonotus parvus obtains heat by using thermoconformity and thigmothermism, which is consistent with the patterns presented by other species of anguids.

Automated summary

Temperature is a critical factor affecting organisms, with Gerrhonotus parvus relying more on substrate temperature than air temperature to regulate body heat. This thigmothermic lizard demonstrates tendencies of using thermoconformity for heat regulation.