Differing Diel Patterns of Temperature Selection in Two Sympatric Desmognathus
Despite the potential constraints imposed by cutaneous respiration and nocturnality, some salamanders actively thermoregulate when conditions permit. We measured substrate temperature selection in two species of Desmognathus in a moist thermal gradient in the laboratory. Desmognathus monticola selected significantly higher temperatures than Desmognathus quadramaculatus. Although the substrate temperatures selected by D. quadramaculatus did not vary over time (mean ± 1 SE = 13.6 ± 1.1 C), D. monticola selected significantly higher temperatures at night than during the day. Mean temperatures selected by D. monticola were 14.0 ± 1.5 C from 1200–1600 h and 19.7 ± 1.6 C from 2000–0000 h. This difference in temporal patterns is consistent with field behavior, because D. monticola is more frequently found away from water at night than is D. quadramaculatus.Abstract
Substrate temperatures selected by Desmognathus monticola (open circles) and Desmognathus quadramaculatus (closed circles) in a laboratory thermal gradient. Each circle represents the mean selected temperature of nine salamanders. The vertical lines represent 1 SE above or below each mean. The horizontal black line indicates scotophase
Frequency of substrate temperatures selected by Desmognathus quadramaculatus (A) and Desmognathus monticola during the day when the lights were on (B) and during the night when the lights were off (C). Each bar represents a 2 C range of selected substrate temperatures